Passivated microelectromechanical structures and methods

ABSTRACT

This disclosure provides systems, methods and apparatus including devices that include layers of passivation material covering at least a portion of an exterior surface of a thin film component within a microelectromechanical device. The thin film component may include an electrically conductive layer that connects via an anchor to a conductive surface on a substrate. The disclosure further provides processes for providing a first layer of passivation material on an exterior surface of a thin film component and for electrically connecting that thin film component to a conductive surface on a substrate. The disclosure further provides processes for providing a second layer of passivation material on any exposed surfaces of the thin film component after release of the microelectromechanical device.

PRIORITY CLAIM

This application claims priority to, and is a continuation-in-part of,U.S. application Ser. No. 14/502,255, filed Sep. 30, 2014, and entitled“PASSIVATED MICROELECTROMECHANICAL STRUCTURES AND METHODS,” which ishereby incorporated by reference in its entirety and for all purposes.

TECHNICAL FIELD

This disclosure relates to microelectromechanical systems and inparticular to microelectromechanical systems having components withpassivated exterior surfaces, and to devices formed from such passivatedcomponents and processes for forming such devices.

DESCRIPTION OF THE RELATED TECHNOLOGY

Electromechanical systems (EMS) include devices having electrical andmechanical elements, actuators, transducers, sensors, optical componentssuch as mirrors and optical films, and electronics. EMS devices orelements can be manufactured at a variety of scales including, but notlimited to, microscales and nanoscales. For example,microelectromechanical systems (MEMS) devices can include structureshaving sizes ranging from about a micron to hundreds of microns or more.Nanoelectromechanical systems (NEMS) devices can include structureshaving sizes smaller than a micron including, for example, sizes smallerthan several hundred nanometers. Electromechanical elements may becreated using deposition, etching, lithography, and/or othermicromachining processes that etch away parts of substrates and/ordeposited material layers, or that add layers to form electrical andelectromechanical devices.

Certain MEMS devices, including certain MEMS displays, requireoverlapping layers of structures. The overlapped layers can have a firstlayer that attaches to a substrate and a second layer that connects tothe first layer and uses the first layer as an anchor to hold the secondlayer away from the substrate surface, similar to the way columns in ahouse can hold a roof above a foundation.

Once formed, the layers are sometimes passivated. Passivation renders asemiconductor material inert. Essentially, passivation provides aninsulating coating over the semiconductor surface. Passivatedsemiconductor surfaces can make contact with other surfaces withoutcreating a short circuit that can damage the device.

The current process for passivating overlapping layers is complex. Topassivate both layers, a passivation agent, often a gas must travel passthe second layer to contact the first layer to passivate that firstlayer. Today, existing processes use Atomic Layer Deposition (ALD).However, the ALD process is slow and tends to leave particles that cancause sticking and device failure. Thus, there remains a need forimproved structures and processes for forming MEMS devices.

SUMMARY

The systems, methods and devices of this disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein.

One innovative aspect of the subject matter described in this disclosurecan be implemented in a MEMS device. The MEMS device may include acomponent, such as a shutter, an actuator, a beam, or some othercomponent that is part of the MEMS device. The component typically isformed from a thin film of semiconductor material, such as amorphoussilicon, and typically responds to an electrical control signal. In oneimplementation described herein, the MEMS device includes a first beamand a second beam. The first and second beams are supported by asubstrate and the first beam is arranged between the substrate and thesecond beam. Both beams have an exterior surface that carries a layer ofpassivation material. The first beam and the second beam each have armsthat extend toward the surface of the substrate. The arms may be thinfilm bodies that are connected together in an overlapping arrangementand form the sidewall of an anchor that extends from the surface of thesubstrate. The anchor is capable of holding the first and second beamsoff the surface of the substrate. In another innovative aspect, thedevice is formed on a substrate that includes a conductive surface andthe device includes an anchor that is in contact with the conductivesurface on the substrate. Both the first and second beams have a layerof conductive material and both beams attach to the anchor and theelectrical layer of at least one of the beams connects to the conductivesurface of the substrate.

In another innovative aspect of the subject matter described herein,processes form MEMS devices having two overlapping beams that aresuspended above a substrate. The overlapping beams can includeelectromechanical components that respond to an electrical signal,typically to move between two or more positions. The process may formthe beams with passivated exterior surfaces. The processes may deposit alayer of passivation material on the substrate. The processes may formthe first beam by depositing material onto the passivation layer. Oncethe beam is formed, the process may cover the exposed surface of thebeam with a layer of passivation material. A mold may be deposited onthe first beam, and the mold may be covered with a passivation layer.The process may form the second beam by depositing material on to thepassivation material. Once the second beam is formed, the process maycover the exposed surface of the second beam with a layer of passivationmaterial. The mold may be washed away and the beams are left in placeand arranged with the first beam placed adjacent the substrate and thesecond beam spaced away from the first beam.

In some implementations, the systems and methods described hereininclude devices having a substrate having a surface, a first thin filmbeam and a second thin film beam, the first beam being arranged betweenthe substrate and the second thin film beam, and the first thin filmbeam being spaced away from the substrate and the second beam, and thefirst beam having a first arm and the second beam having a second arm,each arm extending toward the surface of the substrate, and the firstarm being joined to and overlapping the second arm and the first andsecond arms forming an anchor capable of holding the first beam and thesecond beam a distance away from the substrate. In some implementations,the devices further include a layer of passivation material covering anexterior surface of the first beam. In some implementations, the deviceshave a layer of passivation material covering an exterior surface of thesecond beam.

In some implementations, the devices also include a conductive layerwithin the anchor, and the substrate has a conductive surface in contactwith the conductive layer and the conductive layer extends into thefirst beam and the second beam. In some implementations, the conductivelayer within the anchor includes a first and a second layer ofconductive material coupled to the first beam and the second beamrespectively.

In some implementations, the substrate includes a glass substrate and insome implementations the first beam includes a movable mechanical bodythat may include a movable sidewall beam having an aspect ratio ofgreater than about 4:1. The movable sidewall beam may include aconformal layer of passivation material having a tapered edge. In someimplementations, the second beam includes one or more apertures.

In some implementations the first beam is spaced a distance of betweenabout 0.3 μm and 10 μm from the second beam and in some implementationsthe device has a plurality of spacers for holding a plate away from thesecond beam. In some implementations, the device is a display thatincludes a controller, a processor and a memory for creating imagesthrough light modulators formed from the first and second beams of thedevice.

In another aspect, the systems and methods described herein includeprocesses for forming a thin film device. The processes may includedepositing a conductive pad on a substrate, depositing a mold forforming a first thin film beam. The process may deposit a layer ofpassivation material on the mold, and deposit at least one thin filmlayer on the passivation material to form at least part of the firstthin film beam. The process may deposit a layer of passivation materialover the first thin film beam, deposit a mold over the layer ofpassivation material for forming a second thin film beam, and deposit atleast one thin film layer over the mold to form a second thin film beam.The process may release the first thin film beam and the second thinfilm beam from the mold to form a first beam having a passivationmaterial on an exterior surface and being spaced from the substrate anda second beam spaced from and overlapping the first beam. In someimplementations, the process may have the conductive pad in physicalcontact with the first thin film beam or the second thin film beam.

In some implementations, the process may etch the first thin film beamto form components of a MEMS device. In some implementations, theprocess may deposit at least one thin film layer on to the passivationmaterial and may deposit a layer of passivation material, a layer ofamorphous silicon and a layer of metal.

In some implementations, the process may deposit at least one thin filmlayer includes forming a light modulator for modulating light. Theprocess may form a via through the first thin film beam and the secondthin film beam and extending to the conductive pad, and form an anchorwithin the via for supporting the first thin film beam and the secondthin film beam. The process may further form a side wall of the anchorfrom an arm connected to the first thin film beam and from an armconnected to the second thin film beam.

The process may further provide within the arm of the first thin filmbeam or the arm of the second thin film beam a conductive material forconnecting the first thin film beam or the second thin film beam to theconductive pad. The process may have one of the first thin film beamsand the second thin film beams connects to the conductive pad and theother thin film beam is spaced away from the conductive pad andelectrically connected to the thin film beam connected to the conductivepad.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in a MEMS device including a substrate, afirst thin film beam over the substrate, a second thin film beam overthe first thin film beam, an inner passivation layer partially coveringan exterior surface of the second thin film beam and partially coveringan exterior surface of the first thin film beam, and an outerpassivation layer over the inner passivation layer and covering theinner passivation layer, the exterior surface of the second thin filmbeam, and the exterior surface of the first thin film beam. The firstthin film beam includes one or more electrodes and is arranged betweenthe substrate and the second thin film beam and spaced away from thesubstrate and the second thin film beam, where the second thin film beamincludes one or more apertures.

In some implementations, each of the one or more electrodes includes atop surface, a bottom surface, and sidewalls, the inner passivationlayer covering at least the sidewalls of the one or more electrodes, andthe outer passivation layer covering at least the top and bottomsurfaces of the one or more electrodes. In some implementations, thefirst thin film beam includes a first conductive layer, where thesubstrate includes a conductive surface in contact with the firstconductive layer. In some implementations, the first thin film beamfurther includes a second conductive layer, the second conductive layerbeing identical in composition with the first conductive layer andconnected to the second thin film beam. In some implementations, thesecond conductive layer is an etch stop layer. In some implementations,the first thin film beam further includes a metallic layer between thefirst conductive layer and the second conductive layer, one or more ofthe first conductive layer, the metallic layer, and the secondconductive layer being substantially opaque to light. In someimplementations, a thickness of the second passivation layer is lessthan about 1000 Å.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in a MEMS device including a substrate, afirst thin film beam over the substrate, a second thin film beam overthe first thin film beam, first means for passivating the MEMS devicepartially covering an exterior surface of the second thin film beam andpartially covering an exterior surface of the first thin film beam, andsecond means for passivating the MEMS device over the first passivatingmeans, the second passivating means covering the first passivatingmeans, the exterior surface of the second thin film beam, and theexterior surface of the first thin film beam. The first thin film beamincludes one or more electrodes and is arranged between the substrateand the second thin film beam and spaced away from the substrate and thesecond thin film beam, where the second thin film beam includes one ormore apertures.

In some implementations, each of the one or more electrodes includes atop surface, a bottom surface, and sidewalls, the first passivatingmeans covering at least the sidewalls of the one or more electrodes, andthe second passivating means covering at least the top and bottomsurfaces of the one or more electrodes. In some implementations, thefirst thin film beam includes a first conductive layer, where thesubstrate includes a conductive surface in contact with the firstconductive layer.

Another innovative aspect of the subject matter described in thisdisclosure can be implemented in a method of manufacturing a MEMS deviceincluding providing a substrate, forming a first mold for forming afirst thin film beam over the substrate, forming a first pre-releaselayer of passivating material on the first mold, forming the first thinfilm beam over the first mold and the first pre-release layer ofpassivating material, forming a second pre-release layer of passivatingmaterial over the first thin film beam, forming a second mold over thesecond layer of passivating material for forming a second thin filmbeam, forming the second thin film beam over the second mold, releasingthe first thin film beam and the second thin film beam from the firstmold and the second mold so that the first layer and the second layer ofpassivating material partially covers an exterior surface of the firstthin film beam, the first thin film beam being spaced from the substrateand the second thin film beam spaced from and overlapping the first thinfilm beam, and forming a post-release layer of passivating material tocover the exterior surface of the second thin film beam and the firstthin film beam.

In some implementations, the method further includes a third pre-releaselayer of passivating material over the second thin film beam prior toreleasing the first and the second thin film beams. In someimplementations, forming the first thin film beam includes depositing afirst mask over portions of the first pre-release layer of passivatingmaterial, etching at least some of the first pre-release layer ofpassivating material, depositing a conductive layer over the firstpre-release layer of passivating material and over the first mold, anddepositing a metallic layer on the conductive layer. In someimplementations, forming the first thin film beam includesanisotropically etching at least some of the first pre-release layer ofpassivating material, depositing a first conductive layer over the firstpre-release layer of passivating material and the first mold, depositinga metallic layer on the first conductive layer, and depositing a secondconductive layer on the metallic layer, the second conductive layerbeing identical in composition with the first conductive layer.

Details of one or more implementations of the subject matter describedin this disclosure are set forth in the accompanying drawings and thedescription below. Other features, aspects and advantages will becomeapparent from the description, the drawings and the claims. Note thatthe relative dimensions of the following figures may not be drawn toscale.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a schematic diagram of an example direct-viewmicroelectromechanical systems (MEMS)-based display apparatus.

FIG. 1B shows a block diagram of an example host device.

FIGS. 2A and 2B show views of an example dual actuator shutter assembly.

FIGS. 3A and 3B show a MEMS shutter assembly formed on a substrate.

FIG. 4 shows a cross-sectional view of a substrate having a conductivesurface.

FIG. 5 shows the substrate of FIG. 4 having a layer of photoresist.

FIG. 6 shows a mold layer formed on the photoresist of FIG. 5.

FIG. 7 shows a passivation layer deposited over the mold.

FIG. 8 shows additional layers over the mold.

FIG. 9 depicts a pattern of etch resist on the deposited layers.

FIG. 10 depicts the etched surface of the substrate.

FIG. 11 depicts the substrate with the etch resist removed.

FIG. 12 shows the substrate with a second layer of passivation material.

FIG. 13 shows a mask laid on the passivation layer.

FIG. 14 shows an etched passivation layer.

FIG. 15 shows the mask removed from the substrate.

FIG. 16 shows an anchor layer of resist deposited over the first beam.

FIG. 17 shows the surface exposed by the anchor layer as etched.

FIG. 18 shows a mold for the second beam deposited on the anchor layer.

FIG. 19 shows spacers added to the mold.

FIG. 20 shows the second beam formed on the mold.

FIG. 21 shows a resist layer laid on the second beam.

FIG. 22 shows the surface exposed by the resist layer as etched.

FIG. 23 shows the resist stripped from the substrate.

FIG. 24 shows the first beam and the second beam arranged on thesubstrate.

FIG. 25 is a flow chart of a process for forming a MEMS device firstbeam and a second beam.

FIG. 26 is a flow chart of a process for forming a stacked via.

FIGS. 27A and 27 B show an alternative implementation of a stacked via.

FIGS. 28-41 show cross-sectional schematic views illustrating variousstages of manufacturing an example MEMS device, according to someimplementations.

FIGS. 42A-42D show cross-sectional schematic views illustrating variousstages of passivating a thin film beam on a mold.

FIGS. 43-52 show cross-sectional schematic views illustrating variousstages of manufacturing an example MEMS device, according to some otherimplementations.

FIGS. 53A and 53B show system block diagrams of an example displaydevice that includes a plurality of display elements.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

The following description is directed to certain implementations for thepurposes of describing the innovative aspects of this disclosure.However, a person having ordinary skill in the art will readilyrecognize that the teachings herein can be applied in a multitude ofdifferent ways. The described implementations may be implemented in anydevice, apparatus, or system that is capable of displaying an image,whether in motion (such as video) or stationary (such as still images),and whether textual, graphical or pictorial. The concepts and examplesprovided in this disclosure may be applicable to a variety of displays,such as liquid crystal displays (LCDs), organic light-emitting diode(OLED) displays, field emission displays, and electromechanical systems(EMS) and microelectromechanical (MEMS)-based displays, in addition todisplays incorporating features from one or more display technologies.

The described implementations may be included in or associated with avariety of electronic devices such as, but not limited to: mobiletelephones, multimedia Internet enabled cellular telephones, mobiletelevision receivers, wireless devices, smartphones, Bluetooth® devices,personal data assistants (PDAs), wireless electronic mail receivers,hand-held or portable computers, netbooks, notebooks, smartbooks,tablets, printers, copiers, scanners, facsimile devices, globalpositioning system (GPS) receivers/navigators, cameras, digital mediaplayers (such as MP3 players), camcorders, game consoles, wrist watches,wearable devices, clocks, calculators, television monitors, flat paneldisplays, electronic reading devices (such as e-readers), computermonitors, auto displays (such as odometer and speedometer displays),cockpit controls and/or displays, camera view displays (such as thedisplay of a rear view camera in a vehicle), electronic photographs,electronic billboards or signs, projectors, architectural structures,microwaves, refrigerators, stereo systems, cassette recorders orplayers, DVD players, CD players, VCRs, radios, portable memory chips,washers, dryers, washer/dryers, parking meters, packaging (such as inelectromechanical systems (EMS) applications includingmicroelectromechanical systems (MEMS) applications, in addition tonon-EMS applications), aesthetic structures (such as display of imageson a piece of jewelry or clothing) and a variety of EMS devices.

The teachings herein also can be used in non-display applications suchas, but not limited to, electronic switching devices, radio frequencyfilters, sensors, accelerometers, gyroscopes, motion-sensing devices,magnetometers, inertial components for consumer electronics, parts ofconsumer electronics products, varactors, liquid crystal devices,electrophoretic devices, drive schemes, manufacturing processes andelectronic test equipment. Thus, the teachings are not intended to belimited to the implementations depicted solely in the Figures, butinstead have wide applicability as will be readily apparent to onehaving ordinary skill in the art.

The devices, systems and methods described herein, in one aspect,include MEMS devices that have two beams arranged over a substratesurface. The thin film beams have a passivation coating on an exteriorsurface of the beam. Typically, the beams are arranged to have a firstbeam positioned above the surface of a substrate and the second beam ispositioned above the first beam. The terms “above” or “below” arerelative terms in as much as whether a beam is seen as above or belowdepends upon the orientation of the larger MEMS device. In either case,both beams are spaced a distance from the surface of the substrate andthe first beam is disposed between the substrate and the second beam. Insome implementations, the first and second beams may be planes of thinfilms, such as amorphous silicon (aSi). In some implementations, thebeams are thin films formed into microelectromechanical components.Typically these components are movable structures that respond toelectrical control signals.

Components in a MEMS device may have dimensions that are measured inmicrons and be measured from a few to millions of microns. Thecomponents can be any mechanical or electrical components, such as ashutter, mirror, actuator, aperture, motor, cantilever beam or anycomponent of a mechanical and/or electrical system.

In some implementations, the MEMS device can include one or morepassivation layers formed prior to release, and one or more additionalpassivation layers formed after release.

Particular implementations of the subject matter described in thisdisclosure can be implemented to realize one or more of the followingpotential advantages. In one aspect, the processes can eliminate orreduce the need for passivation process after the release of the beams.Additionally, by shaping the passivation coating by using a deposit andetch process, the process can eliminate or reduce the need for a padopen process to expose covered pads or apertures. Additionally, theprocess may improve yield by reducing the creation of loose particlescaused by complex passivation processes. Additionally, providing apassivation layer after release can eliminate or otherwise reduce theoccurrence of leakage paths that may result from exposed surfaces in thefirst or second thin film beams.

FIG. 1A shows a schematic diagram of an example direct-view MEMS-baseddisplay apparatus 100. The display apparatus 100 includes a plurality oflight modulators 102 a-102 d (generally light modulators 102) arrangedin rows and columns. In the display apparatus 100, the light modulators102 a and 102 d are in the open state, allowing light to pass. The lightmodulators 102 b and 102 c are in the closed state, obstructing thepassage of light. By selectively setting the states of the lightmodulators 102 a-102 d, the display apparatus 100 can be utilized toform an image 104 for a backlit display, if illuminated by a lamp orlamps 105. In another implementation, the apparatus 100 may form animage by reflection of ambient light originating from the front of theapparatus. In another implementation, the apparatus 100 may form animage by reflection of light from a lamp or lamps positioned in thefront of the display, i.e., by use of a front light.

In some implementations, each light modulator 102 corresponds to a pixel106 in the image 104. In some other implementations, the displayapparatus 100 may utilize a plurality of light modulators to form apixel 106 in the image 104. For example, the display apparatus 100 mayinclude three color-specific light modulators 102. By selectivelyopening one or more of the color-specific light modulators 102corresponding to a particular pixel 106, the display apparatus 100 cangenerate a color pixel 106 in the image 104. In another example, thedisplay apparatus 100 includes two or more light modulators 102 perpixel 106 to provide a luminance level in an image 104. With respect toan image, a pixel corresponds to the smallest picture element defined bythe resolution of image. With respect to structural components of thedisplay apparatus 100, the term pixel refers to the combined mechanicaland electrical components utilized to modulate the light that forms asingle pixel of the image.

The display apparatus 100 is a direct-view display in that it may notinclude imaging optics typically found in projection applications. In aprojection display, the image formed on the surface of the displayapparatus is projected onto a screen or onto a wall. The displayapparatus is substantially smaller than the projected image. In a directview display, the image can be seen by looking directly at the displayapparatus, which contains the light modulators and optionally abacklight or front light for enhancing brightness and/or contrast seenon the display.

Direct-view displays may operate in either a transmissive or reflectivemode. In a transmissive display, the light modulators filter orselectively block light which originates from a lamp or lamps positionedbehind the display. The light from the lamps is optionally injected intoa lightguide or backlight so that each pixel can be uniformlyilluminated. Transmissive direct-view displays are often built ontotransparent substrates to facilitate a sandwich assembly arrangementwhere one substrate, containing the light modulators, is positioned overthe backlight. In some implementations, the transparent substrate can bea glass substrate (sometimes referred to as a glass plate or panel), ora plastic substrate. The glass substrate may be or include, for example,a borosilicate glass, wine glass, fused silica, a soda lime glass,quartz, artificial quartz, Pyrex, or other suitable glass material.

Each light modulator 102 can include a shutter 108 and an aperture 109.To illuminate a pixel 106 in the image 104, the shutter 108 ispositioned such that it allows light to pass through the aperture 109.To keep a pixel 106 unlit, the shutter 108 is positioned such that itobstructs the passage of light through the aperture 109. The aperture109 is defined by an opening patterned through a reflective orlight-absorbing material in each light modulator 102.

The display apparatus also includes a control matrix coupled to thesubstrate and to the light modulators for controlling the movement ofthe shutters. The control matrix includes a series of electricalinterconnects (such as interconnects 110, 112 and 114), including atleast one write-enable interconnect 110 (also referred to as a scan lineinterconnect) per row of pixels, one data interconnect 112 for eachcolumn of pixels, and one common interconnect 114 providing a commonvoltage to all pixels, or at least to pixels from both multiple columnsand multiples rows in the display apparatus 100. In response to theapplication of an appropriate voltage (the write-enabling voltage,V_(WE)), the write-enable interconnect 110 for a given row of pixelsprepares the pixels in the row to accept new shutter movementinstructions. The data interconnects 112 communicate the new movementinstructions in the form of data voltage pulses. The data voltage pulsesapplied to the data interconnects 112, in some implementations, directlycontribute to an electrostatic movement of the shutters. In some otherimplementations, the data voltage pulses control switches, such astransistors or other non-linear circuit elements that control theapplication of separate drive voltages, which are typically higher inmagnitude than the data voltages, to the light modulators 102. Theapplication of these drive voltages results in the electrostatic drivenmovement of the shutters 108.

The control matrix also may include, without limitation, circuitry, suchas a transistor and a capacitor associated with each shutter assembly.In some implementations, the gate of each transistor can be electricallyconnected to a scan line interconnect. In some implementations, thesource of each transistor can be electrically connected to acorresponding data interconnect. In some implementations, the drain ofeach transistor may be electrically connected in parallel to anelectrode of a corresponding capacitor and to an electrode of acorresponding actuator. In some implementations, the other electrode ofthe capacitor and the actuator associated with each shutter assembly maybe connected to a common or ground potential. In some otherimplementations, the transistor can be replaced with a semiconductingdiode, or a metal-insulator-metal switching element.

FIG. 1B shows a block diagram of an example host device 120 (i.e., cellphone, smart phone, PDA, MP3 player, tablet, e-reader, netbook,notebook, watch, wearable device, laptop, television, or otherelectronic device). The host device 120 includes a display apparatus 128(such as the display apparatus 100 shown in FIG. 1A), a host processor122, environmental sensors 124, a user input module 126, and a powersource.

The display apparatus 128 includes a plurality of scan drivers 130 (alsoreferred to as write enabling voltage sources), a plurality of datadrivers 132 (also referred to as data voltage sources), a controller134, common drivers 138, lamps 140-146, lamp drivers 148 and an array ofdisplay elements 150, such as the light modulators 102 shown in FIG. 1A.The scan drivers 130 apply write enabling voltages to scan lineinterconnects 131. The data drivers 132 apply data voltages to the datainterconnects 133.

In some implementations of the display apparatus, the data drivers 132are capable of providing analog data voltages to the array of displayelements 150, especially where the luminance level of the image is to bederived in analog fashion. In analog operation, the display elements aredesigned such that when a range of intermediate voltages is appliedthrough the data interconnects 133, there results a range ofintermediate illumination states or luminance levels in the resultingimage. In some other implementations, the data drivers 132 are capableof applying a reduced set, such as 2, 3 or 4, of digital voltage levelsto the data interconnects 133. In implementations in which the displayelements are shutter-based light modulators, such as the lightmodulators 102 shown in FIG. 1A, these voltage levels are designed toset, in digital fashion, an open state, a closed state, or otherdiscrete state to each of the shutters 108. In some implementations, thedrivers are capable of switching between analog and digital modes.

The scan drivers 130 and the data drivers 132 are connected to a digitalcontroller circuit 134 (also referred to as the controller 134). Thecontroller 134 sends data to the data drivers 132 in a mostly serialfashion, organized in sequences, which in some implementations may bepredetermined, grouped by rows and by image frames. The data drivers 132can include series-to-parallel data converters, level-shifting, and forsome applications digital-to-analog voltage converters.

The display apparatus optionally includes a set of common drivers 138,also referred to as common voltage sources. In some implementations, thecommon drivers 138 provide a DC common potential to all display elementswithin the array 150 of display elements, for instance by supplyingvoltage to a series of common interconnects 139. In some otherimplementations, the common drivers 138, following commands from thecontroller 134, issue voltage pulses or signals to the array of displayelements 150, for instance global actuation pulses which are capable ofdriving and/or initiating simultaneous actuation of all display elementsin multiple rows and columns of the array.

Each of the drivers (such as scan drivers 130, data drivers 132 andcommon drivers 138) for different display functions can betime-synchronized by the controller 134. Timing commands from thecontroller 134 coordinate the illumination of red, green, blue and whitelamps (140, 142, 144 and 146 respectively) via lamp drivers 148, thewrite-enabling and sequencing of specific rows within the array ofdisplay elements 150, the output of voltages from the data drivers 132,and the output of voltages that provide for display element actuation.In some implementations, the lamps are light emitting diodes (LEDs).

The controller 134 determines the sequencing or addressing scheme bywhich each of the display elements can be re-set to the illuminationlevels appropriate to a new image 104. New images 104 can be set atperiodic intervals. For instance, for video displays, color images orframes of video are refreshed at frequencies ranging from 10 to 300Hertz (Hz). In some implementations, the setting of an image frame tothe array of display elements 150 is synchronized with the illuminationof the lamps 140, 142, 144 and 146 such that alternate image frames areilluminated with an alternating series of colors, such as red, green,blue and white. The image frames for each respective color are referredto as color subframes. In this method, referred to as the fieldsequential color method, if the color subframes are alternated atfrequencies in excess of 20 Hz, the human visual system (HVS) willaverage the alternating frame images into the perception of an imagehaving a broad and continuous range of colors. In some otherimplementations, the lamps can employ primary colors other than red,green, blue and white. In some implementations, fewer than four, or morethan four lamps with primary colors can be employed in the displayapparatus 128.

In some implementations, where the display apparatus 128 is designed forthe digital switching of shutters, such as the shutters 108 shown inFIG. 1A, between open and closed states, the controller 134 forms animage by the method of time division gray scale. In some otherimplementations, the display apparatus 128 can provide gray scalethrough the use of multiple display elements per pixel.

In some implementations, the data for an image state is loaded by thecontroller 134 to the array of display elements 150 by a sequentialaddressing of individual rows, also referred to as scan lines. For eachrow or scan line in the sequence, the scan driver 130 applies awrite-enable voltage to the write enable interconnect 131 for that rowof the array of display elements 150, and subsequently the data driver132 supplies data voltages, corresponding to desired shutter states, foreach column in the selected row of the array. This addressing processcan repeat until data has been loaded for all rows in the array ofdisplay elements 150. In some implementations, the sequence of selectedrows for data loading is linear, proceeding from top to bottom in thearray of display elements 150. In some other implementations, thesequence of selected rows is pseudo-randomized, in order to mitigatepotential visual artifacts. And in some other implementations, thesequencing is organized by blocks, where, for a block, the data for acertain fraction of the image is loaded to the array of display elements150. For example, the sequence can be implemented to address every fifthrow of the array of the display elements 150 in sequence.

In some implementations, the addressing process for loading image datato the array of display elements 150 is separated in time from theprocess of actuating the display elements. In such an implementation,the array of display elements 150 may include data memory elements foreach display element, and the control matrix may include a globalactuation interconnect for carrying trigger signals, from the commondriver 138, to initiate simultaneous actuation of the display elementsaccording to data stored in the memory elements.

In some implementations, the array of display elements 150 and thecontrol matrix that controls the display elements may be arranged inconfigurations other than rectangular rows and columns. For example, thedisplay elements can be arranged in hexagonal arrays or curvilinear rowsand columns.

The host processor 122 generally controls the operations of the hostdevice 120. For example, the host processor 122 may be a general orspecial purpose processor for controlling a portable electronic device.With respect to the display apparatus 128, included within the hostdevice 120, the host processor 122 outputs image data as well asadditional data about the host device 120. Such information may includedata from environmental sensors 124, such as ambient light ortemperature; information about the host device 120, including, forexample, an operating mode of the host or the amount of power remainingin the host device's power source; information about the content of theimage data; information about the type of image data; and/orinstructions for the display apparatus 128 for use in selecting animaging mode.

In some implementations, the user input module 126 enables theconveyance of personal preferences of a user to the controller 134,either directly, or via the host processor 122. In some implementations,the user input module 126 is controlled by software in which a userinputs personal preferences, for example, color, contrast, power,brightness, content, and other display settings and parameterspreferences. In some other implementations, the user input module 126 iscontrolled by hardware in which a user inputs personal preferences. Insome implementations, the user may input these preferences via voicecommands, one or more buttons, switches or dials, or withtouch-capability. The plurality of data inputs to the controller 134direct the controller to provide data to the various drivers 130, 132,138 and 148 which correspond to optimal imaging characteristics.

The environmental sensor module 124 also can be included as part of thehost device 120. The environmental sensor module 124 can be capable ofreceiving data about the ambient environment, such as temperature and orambient lighting conditions. The sensor module 124 can be programmed,for example, to distinguish whether the device is operating in an indooror office environment versus an outdoor environment in bright daylightversus an outdoor environment at nighttime. The sensor module 124communicates this information to the display controller 134, so that thecontroller 134 can optimize the viewing conditions in response to theambient environment.

FIGS. 2A and 2B show views of an example dual actuator shutter assembly200. The dual actuator shutter assembly 200, as depicted in FIG. 2A, isin an open state. FIG. 2B shows the dual actuator shutter assembly 200in a closed state. The shutter assembly 200 includes actuators 202 and204 on either side of a shutter 206. Each actuator 202 and 204 isindependently controlled. A first actuator, a shutter-open actuator 202,serves to open the shutter 206. A second opposing actuator, theshutter-close actuator 204, serves to close the shutter 206. Each of theactuators 202 and 204 can be implemented as compliant beam electrodeactuators. The actuators 202 and 204 open and close the shutter 206 bydriving the shutter 206 substantially in a plane parallel to an aperturelayer 207 over which the shutter is suspended. The shutter 206 issuspended a short distance over the aperture layer 207 by anchors 208attached to the actuators 202 and 204. Having the actuators 202 and 204attach to opposing ends of the shutter 206 along its axis of movementreduces out of plane motion of the shutter 206 and confines the motionsubstantially to a plane parallel to the substrate (not depicted).

In the depicted implementation, the shutter 206 includes two shutterapertures 212 through which light can pass. The aperture layer 207includes a set of three apertures 209. In FIG. 2A, the shutter assembly200 is in the open state and, as such, the shutter-open actuator 202 hasbeen actuated, the shutter-close actuator 204 is in its relaxedposition, and the centerlines of the shutter apertures 212 coincide withthe centerlines of two of the aperture layer apertures 209. In FIG. 2B,the shutter assembly 200 has been moved to the closed state and, assuch, the shutter-open actuator 202 is in its relaxed position, theshutter-close actuator 204 has been actuated, and the light blockingportions of the shutter 206 are now in position to block transmission oflight through the apertures 209 (depicted as dotted lines).

Each aperture has at least one edge around its periphery. For example,the rectangular apertures 209 have four edges. In some implementations,in which circular, elliptical, oval, or other curved apertures areformed in the aperture layer 207, each aperture may have a single edge.In some other implementations, the apertures need not be separated ordisjointed in the mathematical sense, but instead can be connected. Thatis to say, while portions or shaped sections of the aperture maymaintain a correspondence to each shutter, several of these sections maybe connected such that a single continuous perimeter of the aperture isshared by multiple shutters.

In order to allow light with a variety of exit angles to pass throughthe apertures 212 and 209 in the open state, the width or size of theshutter apertures 212 can be designed to be larger than a correspondingwidth or size of apertures 209 in the aperture layer 207. In order toeffectively block light from escaping in the closed state, the lightblocking portions of the shutter 206 can be designed to overlap theedges of the apertures 209. FIG. 2B shows an overlap 216, which in someimplementations can be predefined, between the edge of light blockingportions in the shutter 206 and one edge of the aperture 209 formed inthe aperture layer 207.

The electrostatic actuators 202 and 204 are designed so that theirvoltage-displacement behavior provides a bi-stable characteristic to theshutter assembly 200. For each of the shutter-open and shutter-closeactuators, there exists a range of voltages below the actuation voltage,which if applied while that actuator is in the closed state (with theshutter being either open or closed), will hold the actuator closed andthe shutter in position, even after a drive voltage is applied to theopposing actuator. The minimum voltage needed to maintain a shutter'sposition against such an opposing force is referred to as a maintenancevoltage V_(m).

The systems and methods described herein may be employed to form anytype of microelectromechancial device, including any device havingfeatures with dimensions comparable to the dimensions that are achievedusing processes for forming semiconductor devices, such as processesemployed for forming patterns of semiconductor material on a surface. AMEMS device can include, without limitations, a light modulator, amicrophone, a sensor, piezoresistors, piezoelectric crystals, devicesfor electromechanical actuation, filters, devices for signaltransduction and any other type of component typically employed withsemiconductor based electronic devices. For the sake of illustrationonly, the systems and methods described herein will be discussed withreference to a MEMS shutter assembly for use in a display. FIGS. 3A and3B show a MEMS shutter assembly formed on a substrate. In particular,FIG. 3A is an isometric view of a portion of an array 300 of shutterassemblies, where each shutter assembly may provide a pixel within animage of a display. The array 300 of shutter assemblies includes fourpixels 301 arranged in rows and columns, but a typical display will havethousands of pixels. Each pixel 301 is a semiconductor device fabricatedon the surface of a substrate 304. In particular, each pixel 301 is asemiconductor device that includes an aperture 354 and a shutterassembly 302, both of which have been fabricated on the substrate 304.The pixels 301 include components such as the shutter assembly 302, anactuator 303, the apertures 354 and electrical interconnect components,such as the depicted data interconnect 308. The individual components ofeach pixel 301, such as the actuator 303, or the shutter assembly 302include semiconductor components manufactured using a process flow thatforms the components as elements carried on the surface of the aperturelayer 350. The aperture layer 350 is a component as well and isdeposited and patterned onto the substrate 304. The aperture layer 350provides apertures that light can pass through to create an image. Insome implementations, the substrate 304 may be a transparent substrate,such as glass, silica, plastic, or some other material suitable forreceiving a layer of semiconductor material that can act as the aperturelayer 350 and be processed to form the different components that make upeach pixel 301. Optionally, a control matrix as described with referenceto FIGS. 1A and 1B, may be fabricated on the aperture layer 350 anddifferent components such as thin film switches, transistors andcapacitors and interconnects, such as the data interconnect 308 may beformed on the aperture layer 350. The processes employed to fabricatethese components can be the typical processes known in the art ofmanufacturing for active matrix arrays for use in displays.

The aperture layer 350 may consist of thin film materials that areprocess-compatible with the active matrix fabricated on that aperturelayer 350. The aperture layer can have holes, such as the apertures 355that may be formed by etching portions of the aperture layer 350 untilthe substrate 304 is exposed. The processes for fabricating holes, suchas the apertures 355 can be the same thin film processing techniquesused to fabricate the active matrix on the aperture layer 350, and onlymask designs or pixel layouts need to be changed to accommodate theformation of aperture holes.

Typically, the aperture layer 350 is deposited as a single thin filmonto the substrate 304. Deposition may be accomplished by evaporation,sputtering, chemical vapor deposition, or any suitable technique. Theaperture layer 350 may be any suitable semiconductor material, such asamorphous or polycrystalline silicon (Si), geranium (Ge), a galliumarsenide (GaAs) material, or any other suitable material that can bedeposited in films having in excess of 500 nm.

FIG. 3A further depicts that the pixels 301 are MEMS devices thatinclude mechanical components that are movable relative to the aperturelayer 350. In one process, the components of the pixels 301 are formedusing a mold that can support the deposition of semiconductor materialsthat can be patterned and formed to create the individual components ofthe pixels 301. For example, molds may be used to create plateaus thatwill support the deposition of a semiconductor material, such amorphoussilicon (aSi). The aSi may be laid on the plateau as a thin film. Thedeposited thin film may be hardened and the mold supporting that thinfilm may be etched, washed, or otherwise removed to the leave the thinfilm in place to act as the shutter 302. The shutter 302 is spaced adistance away from the surface of the aperture layer 350. To that end,anchors 311 are formed on the surface of the aperture 350 and extendfrom the surface of the aperture layer 350. Sidewall beams 313 connectbetween the anchors 311 and the shutter 302 to hold the shutter 302 inplace and away from the surface of the aperture layer 350. The sidewallbeams can be movable beams having an aspect ratio of greater than about4 to 1, and perhaps more than 16 to 1, to provide narrow profile and aflexible beam that can be moved by application of an electromotiveforce. The anchors 311 may attach to the substrate 304 to provide astable and secure attachment for the components, such as the shutter302, that are supported by the anchor 311. The anchor 311 may connect toa conductive surface on the substrate 304. The conductive surface cancouple the anchor 311 into electrical communication with the drivercircuits and other elements that can apply electrical signals to thepixel 301 through the anchor 311.

FIG. 3A illustrates one implementation of a MEMS device, and thisillustrated MEMS device has two layers of components. A first layer, theaperture layer 350, lays over the substrate 304 and provides a layer ofsemiconductor material that includes apertures 355.

A second layer is positioned above the aperture layer 350 and overlaps aportion of the aperture layer. This second layer includes the shutter302 and the actuators 303 as well as other components held in place adistance away from the aperture layer 350. In some implementations thefirst layer and the second layer are formed by depositing a first layerof material or a set of layers of material on a mold and then building asecond mold on that layer or layers. Materials may be deposited on thatsecond mold to form the second layer of components. By removing thefirst and second molds, the two layers of components are released toleave the aperture layer 350 proximate the substrate 304 and the shutter302 and the actuator 303 above the substrate layer 350.

In some implementations, the exterior surfaces of the components in thefirst and second layers have a passivation coating. The passivationcoating is deposited on to the first and/or second mold to form anexterior surface of one of the layers of components. After release, thefirst layer of components and second layer of components have apassivated exterior and do not require a passivation process. This canreduce the possibility that deposition of a passivation material overthe movable components, such as the actuators 303, interferes withoperation of those components.

FIG. 3B shows one shutter assembly 302 in cross-section. The shutterassembly 302 includes a first layer 361 of components including theactuators 303, the spring 313 and the shutter 302, and a second layer363 of components, which include the apertures 355. Both layers 361 and363 connect to the anchor 311. Both layers 361 and 363 have a layer ofpassivation material covering at least a portion of the exterior surfaceof the layer. As discussed above, the layers 361 and 363 may be formedfrom one or more thin films of semiconductor material. The layer 361includes an arm 371, formed of thin films of semiconductor material, andextending toward the surface of the substrate 304. The arm 371 forms aportion of the sidewall of the anchor 311. The layer 363 has an arm 373formed of thin films of semiconductor material and extending toward thesurface of the substrate 304. The thin films of arm 373 overlap andconnect to the thin films of arm 371 and form a portion of the sidewallof anchor 311. The bottom wall of anchor 311 contacts the conductivesurface of the interconnect 308. The anchor 311 holds the layers 361 and363 away from the surface of the substrate 304 and in an overlappingarrangement.

To form the components of the pixel 301, resist material is deposited onthe surface of the substrate 304 to form a mold. The mold may be used tocast the different components of the pixel 301, and can provide theshape, or at least part of the shape of each component of the pixel 301.A layer of passivation material may be deposited over the mold andadditional thin film layers may be deposited to build layers on thepassivation layer and form the components within the layer. The resultof these depositions is a thin film structure, typically a beam, builton top of the mold with an exterior layer of passivation material.

Another mold may be formed over this first beam and that mold may allowfor the formation of another beam that includes the apertures 355 of thepixel 301. To this end, one or more layers of material may be depositedon this other mold and these layers may be covered with a layer ofpassivation material. Once the deposited layers have formed thecomponents on the mold, the mold material is washed, etched or otherwiseremoved to leave the components in place with a passivated exteriorsurface and attached to the substrate.

FIG. 4 shows a cross-sectional view of a substrate having a conductivesurface. FIG. 4 shows one stage of device fabrication of someimplementations of the devices of the type described herein, including,for example, devices that have a substrate with a conductive surface andwith two thin film beams, both of which are spaced away from thesubstrate and held away from the substrate by an anchor. The two beamsmay be arranged so that one beam overlaps the other beam. In someimplementations, the anchor has a sidewall that is formed from the armsthat are extending from the two beams. The arms may be joined andoverlapping to form a thin film beam that provides one sidewall of theanchor. In particular, FIG. 4 shows a substrate 350 having a layer ofmetal 352 deposited on the substrate 350, and a layer of passivationmaterial 354 deposited on the metal layer 352. In one implementation,the substrate is formed of glass. The glass substrate can be formed ofdisplay grade glass, soda lime glass, among other examples. In someimplementations, the glass substrate has a thickness greater than orequal to about 0.2 millimeters (mm), to provide the desired amount ofrigidity. In alternative implementations, other materials such assilicon, plastic, or metal can be used in place of or in addition toglass as the material for the rigid substrate. In some implementations,the glass substrate includes a coating such as SiO2, SiNx, and/orvarious metals. The substrate can also be formed of a ceramic, such asAlOx, YOx, BNx, SiCx, AlNx, or GaNx. In other implementations, thesubstrate is formed of a compound semiconductor, such as GaAs, GaP, orGaN. In further implementations, the substrate is a Si wafer, forexample, with a thickness greater than or equal to about 0.1 mm or 0.2mm. One or more coatings such as SiO2, SiNx, and/or some materials canbe applied to the Si wafer. In further implementations, metal substratesformed of various kinds of metals such as stainless steel, Al, Ti, Cr,Cu, W, Ni, V, Mo, Co, Ta, Fe, Pt, Au, Zn, Sn and/or alloys of suchmetals, for instance, AlCu, AlSi, AlCu, AlTi, AlSc, AlNd, AlCr, AlCo,AlTiSi, AlCuSi, AlSc, AlY, CrCu, CrMo, CrRu, CrTa, CrTi, CrV, CoNi, NiV,AlFe, NiFe, WSi, and WTi can be used. The various substrates describedherein can be laminated, in some implementations.] The metal layer 352has a recess 356 that is filled with material from the passivation layer354. The passivation layer 354 has a recess as well that is filled witha conductive material 358. The conductive material 358 forms a pad thatcontacts the metal layer 352. In one implementation, the conductivematerial 358 is indium tin oxide (ITO), or some other suitable materialfor providing an electrical connection with the metal layer 352 andproviding a conductive surface within the passivation layer 354. Inother implementations, the conductive material 358 may be zinc oxides(ZnOx), Titanium (Ti), titanium nitrides (TiNx), molybdeum nitrides(MoNx), tantalum and tantalum nitrides (Ta, TaNx), and multilayers ofdiffusion barrier and aluminum (Al). A diffusion barrier may be Ti, Mo,TiNx, MoNx, Ta and TaNx. The metal layer 352 may be a layer of metalmaterial, such as aluminum (Al), copper (Cu), cobalt (Co), tantalum(Ta), titanium (Ti), molybdenum (Mo), gold (Au), silver (Ag),multilayers of these materials, combinations of these materials andalloys of these materials or some other material that conductselectrical signals sufficiently well to provide electrical signals tothe components of the pixel 301. The metal layer 352 may be a singlelayer of material or a composite of materials, including materialstypically provided to control diffusion and improve conductivity of themetal layer 352.

As noted above, the substrate 350 may be glass, plastic, silicacontaining material, single crystal or amorphous silicon (aSi), othersingle crystalline materials such as quartz or gallium arsenide (GaAs),or any other suitable substrate material that can receive a thin film ofdeposited material. In some implementations the substrate 350 is formedof a transparent material such as optically transmissive forms ofaluminum oxide (Al₂O₃), silicon oxide (SiO₂), silicon nitride (Si₃N₄) orother suitable materials. The passivation layer 354 may be any suitablepassivation material. Typically the passivation layer is silicon nitride(SiNx). The SiNx can form a nitride layer on the surface of the metallayer 352 and may act as a protective layer on the surface of the metal.In some implementations, the passivation layer 354 may also includeSiO₂, SiOxNy and spin on glass (SOG). Optionally, a polymer coating maybe used. In some implementations the polymer coating may include a hightemperature polymer, such as polyimide, benzoclyclobutene (BCB), andmulti-layers of polymer and dielectric films such as SiNx. Furtheroptionally, in some implementations this dielectric layer maybe formedon the passivation layer to provide resistance to ashing, such as oxygenashing. In some implementations, such a dielectric layer may includeSiNx, SiO2 or SiONx. The passivation layer 354 typically provideselectrical stability by isolating components of the MEMS device fromelectrical and chemical conditions that may be in the environment inwhich the MEMS device is operating. The thickness of the metal layer 352and the passivation layer 354 may be selected according to techniquesknown in the art and any suitable thickness can be employed withoutdeparting from the scope hereof. The metal layer 352 provides aconductive surface that is in contact with the conductive material 358.The thickness of the metal layer may typically be 1000 Å-1 um and insome examples may be 300 Å-3 um. The conductive material 358 may be anindium tin oxide (ITO) material which typically is a tin doped indiumoxide, which is a heavily doped semi-conductor material that provides atransparent electrical conductor.

FIG. 5 shows the substrate of FIG. 4 having a layer of photoresist. Inparticular, FIG. 5 shows a layer of photoresist 362 that covers aportion of the passivation layer 355 on the substrate 350. Thephotoresist 362 may be spun on the substrate 350 and patterned toprovide a mold for features of the first layer of components. Thephotoresist layer 362 includes a via 364 that exposes the conductivematerial 358. Additionally, the photoresist layer 362 includes vias 366that expose the passivation layer 355. The vias 366 and 364 allow forthe deposition of materials onto the layers connected to the substrate350. This provides locations for a component, such as an anchor, thatcan connect to the substrate 350. These anchors may be used to supportthe beams that will be suspended over the surface of the substrate 350and that will contain other components of the device, such as theshutters, actuators and apertures. In some implementations, thethickness of the photoresist layer 362 is selected to define thedistance between the substrate 350 and the components, such as theshutters and actuators, that will be in the beam suspended over thesurface of the substrate 350. To this end, the vias 366 and 364 can beseen as molds that form the anchors that can connect to the substrate350 and extend from the substrate 350 and hold components like theshutter 302 away from the substrate 350.

FIG. 6 shows a mold layer formed on the photoresist of FIG. 5. Inparticular, FIG. 6 shows the mold layer 370 deposited on the photoresistlayer 362. The mold layer 370 can be formed from a photoresist materialthat was spun over the substrate, hardened and patterned. The patternsupports the formation of components that can be used in the MEMSdevice. The pattern arises in part from the vias formed within the moldlayer 370. In FIG. 6, the vias include vias 372 that expose thepassivation layer 355, the vias 374 that expose the photoresist layer362 and the via 378 that exposes the conductive material 358. The vias372 and 374 and the upper surface of the mold layer 370 provide thefeatures of the mold that will shape components of the pixel 301, likethe shutter 302, and that can attach to the anchors, such as anchors 311shown in FIG. 3A, formed by the vias 366 and 364 in the layer 362.

FIG. 7 shows a passivation layer over the mold. In particular, FIG. 7shows a passivation layer 382 formed over the mold layer 370. In oneimplementation, the passivation layer 382 is a conformal layer of SiNxthat extends over the mold layer 370 and against sidewalls of the vias372, 378 and 374. In some other implementations the passivation layermay be SiO2, silicon oxynitride (SiNxOy), and AlOx. In someimplementations the passivation layer includes a SiOxNy, and thedeposition process and composition of the SiOxNy may be adjusted toachieve different ranges of mechanical stress. The passivation layer 382is typically an electrical insulator that can act as an exterior surfacefor a component of the MEMS device. To arrange the passivation layer 382as an exterior surface for components in a MEMS device, such as thepixel 301, the process deposits the passivation layer 382 as the layerthat is directly in contact with the mold layer 370. As the mold layer370 will be removed from the substrate 350 during a release process, thepassivation layer 382 will be exposed to the environment of MEMS deviceand will be an exterior surface for the MEMS device. Typically, theprocess will deposit additional materials that can form the thin filmsthat makes up components of the MEMS device, such as the shutters 302and the aperture layer 304 depicted in FIG. 3.

FIG. 8 shows additional layers deposited over the mold. The additionallayers 384 and 386 can be thin films of semiconductor materials such asaSi, titanium (Ti), aluminum (Al) or some other material suitable forforming a component of a MEMS device. In one implementation, the layer384 is a layer of aSi that is deposited as a conformal layer over thepassivation layer 382. The layer 384 of aSi may be optionally baked orotherwise hardened to take the shape of the mold 370, and thereby takethe shape of components in the pixel 301. In one implementation thelayer 386 is a conformal deposition of Ti. The Ti layer 386 may be anopaque layer for use with optical components, like shutters that blockslight from traveling past an aperture 354. Both the layer 384 of aSi andthe layer 386 of Ti can be conductive layers that are capable ofcarrying an electrical signal within the MEMS components being formedover the mold 370. In some implementations where the layers 384 and 386form portions of a shutter for blocking light, one or both of the layersmay be opaque and capable of blocking light.

FIG. 9 depicts a pattern of etch resist on the deposited layers. Inparticular, FIG. 9 depicts an etch resist material deposited as apattern of etch resist 390. The etch resist 390 fills the vias withinthe mold 370, except for the via 378 that is half filled by etch resistmaterial 392 which covers one side wall and a portion of the bottom wallof the via 378. In one implementation, the half-filled via 378 is formedby fully filling the via 378 with etch resist 390 and using a patternedmask to photolithographically select half of the etch resist 390 forremoval by solvent or an isotropic selective dry etch. For a positiveresist made Soluble by exposure to light, a developer may be applied,such as but not being limited to KOH or tetramethylammonium hydroxide(TMAH). Once the selected etch resist 390 is removed, the via 378 isleft half-filled as illustrated. The resist material 390 can be aconventional etch resist material and may be an etch resist materialsuch as a polyamide that has been hard baked. In one implementation, theetch process employed to remove portions of the deposited layers 386,384 and 382 may be anisotropic dry etch process that uses a chlorinebase to etch titanium and amorphous silicon and may include a sulfurfluoride (SF₆) or a carbon fluoride (CF₄) based dry etch for removing aSiNx passivation layer. In any case, an etch process may be employed forthe purpose of etching away portions of the thin films that weredeposited upon the mold layer 370 and within the vias 372, 374 and 378.

FIG. 10 depicts the etched surface of the substrate. In particular, FIG.10 illustrates that the layers 386, 384 and 382 have been removed fromthe mold layer 370 at those locations that were not protected by theetch resist material 390. The bottom wall of the via 378 has been etchedto remove the exposed portions of the layers 386, 384 and 382 and toexpose the conductive surface 358. This process essentially cuts thethin film layers 382, 384 and 386, to the correct size and shape so thatthe thin films are shaped as they should be to form the beam ofcomponents in the pixel 301.

FIG. 11 depicts the substrate with the etch resist 390 and 392 removed.FIG. 11 illustrates components 383 and 385, that are components of theanchors of the MEMS device, formed over the layers 370 and 362. Thecomponents 383 and 385 are spaced away from the surface of the substrate350 by a distance equal to the thickness of the metal layer 352 and thepassivation layer 354. FIGS. 12 through 15 show a process for depositinga passivation layer over the components that were formed by the earlierprocess shown in FIGS. 1-11. Generally, the FIGS. 12 through 15illustrate the process of depositing a passivation layer, and thenetching that layer to have the correct shape for the second beam, suchas the beam 363 of FIG. 3B.

FIG. 12 depicts the substrate with a second layer of passivationmaterial deposited. In particular, FIG. 12 depicts a second passivationlayer 394 that is deposited as a conformal layer of passivationmaterial. The passivation layer 394 covers the exposed surface of themold layer 370, the surface of the thin film layer 386 and extends intothe vias 372, 378 and 374 to provide a conformal layer that coatssidewalls and bottom walls of these vias. Once coated with the secondpassivation layer 394, the process can apply an etch resist.

FIG. 13 depicts a layer of etch resist 396 deposited at select locationsto protect the second passivation layer 394 on certain features of thedevice, such as certain portions of the vias 372, 378 and 374 formedwithin the mold layer 370. The etch resist layer 396 can resist an etchprocess to protect material covered by the resist layer 396. Materialexposed to the etch process may be removed from the substrate 350. Thepattern of the resist layer 396 is selected to allow an etch process toremove portions of the passivation layer 382 from the mold layer 370 andthereby shape the passivation layer 382 to provide the components of thepixel 301 with a passivated exterior surface.

FIG. 14 shows portions of a passivation layer 394 removed by an etchprocess. FIG. 14 illustrates that the exposed portions of thepassivation layer 394 has been removed by an etch process. In oneimplementation the etch process may be anisotropic etch process, such asa CF₄ plasma etch process that can remove a silicon nitride (SiNx)passivation layer. FIG. 14 illustrates that the passivation layer 394has been removed from all areas that were not covered by the etch resist396. FIG. 15 illustrates the etch resist 396 stripped from thesubstrate.

FIG. 15 shows the anchor components 383 and 385 of the MEMS device witha layer of passivation, layer 394, deposited as an exterior conformedcoating. The components 383 and 385 also have a layer of passivationmaterial 382, disposed between the components 383 and 385 and the layer370.

FIG. 16 depicts a layer of photoresist applied to the substrate. Inparticular, FIG. 16 depicts a layer of photoresist 400 deposited acrossthe surface of the substrate with a pattern that can allow forsubsequently deposited layers of material to form elements of componentsof the MEMS device.

FIG. 17 depicts the substrate after an etch process. In particular, FIG.17 depicts the effect of an etch process that is an isotropic dry etchprocess that can remove a passivation layer such as a silicon nitride(SiNx) passivation layer 394. In particular, FIG. 17 shows that the via378 has been etched to remove the passivation layer 394 from thesidewalls and a portion of the bottom wall of via 378 and expose theconducting material 358. Other sections of the SiNx material have alsobeen etched away, leaving and exposing the layer 386 which had beenearlier covered by the second passivation layer 394.

FIG. 18 depicts a mold layer for forming components of a MEMS device. Inparticular, FIG. 18 depicts a mold layer 402 that has been deposited ina pattern across the surface of the photoresist 400. The mold layer 402can provide structure that will allow a subsequently deposited set ofthin film materials to have a shape suitable for forming a beamsuspended over the substrate 350 and having components of a MEMS device,such as the apertures 354 illustrated in FIG. 3A.

FIG. 19 depicts deposition of photoresist material for the purpose ofproviding a spacer component. In particular, FIG. 19 depicts thedeposition of spacers 408 which are portions of photoresist materiallocated on top of certain mold sections 402. The spacer 408 can provideadditional height to the via structures 372 being formed. In oneimplementation, the MEMS device is placed into contact with a secondsubstrate and the spacers 408 can contact the second substrate andprovide part of the mechanical support and that keeps the secondsubstrate separate from the first substrate 350.

FIG. 20 depicts the deposition of several layers of semiconductormaterial over the mold and spacers. In particular, FIG. 20 depicts thedeposition of several layers of semiconductor material, typically an aSilayer as well as a metal layer, such as Ti metal material, and apassivation layer typically a silicon nitride layer (SiNx). The layersare depicted as one on top of the other and shown as elements 410, 412and 414 in FIG. 20. The depicted layers are a conformal set of layers inthat they follow the pattern of the mold 402 and the spacers 408 andprovide conformal deposition on the bottom wall and sidewalls of the via378. The layer 410 may be aSi and conductive. That conductive layer 410is deposited on the bottom of the via 378 and into contact with theconducting surface 358. This allows the anchor 430 being formed withinvia 378 to be in electrical contact with the interconnect layer of theMEMs device. The via 378 has a sidewall 379 that has an arm 391 from thefirst beam stacked against and overlapping with an arm 393 extendingfrom the second beam of components. The two arms 391 and 393 each areformed from three layers of thin films of semiconductor material (asshown by the brackets at the end of the reference line for the referencenumbers 391 and 393. The arms 391 and 393 are joined in an overlappingarrangement to form the sidewall 379 of the anchor 430. The arm 391includes conductive layer 410 that extends from the substrate 350, alongthe sidewall 379 and covers portions of the mold layer 400 that is usedto form the second beam of components, such as the apertures 354 of FIG.3A. The conductive layer 410 is also in contact with the conductivelayer 384. The conductive layer 384 extends from the substrate 350,along the sidewall 379 and covers portions of the mold layer 370 that isused to form the first beam of components, such as the shutters 302 ofFIG. 3A.

FIG. 21 depicts an etch resist material 418 deposited on the substrate.The etch resist material 418 is deposited with a pattern that includesseveral vias 420. The vias 420 expose portions of the deposited layers414, 412 and 410.

FIG. 22 depicts the etched surface of the substrate. In particular, FIG.22 depicts that exposed portion of the material layers 410, 412 and 414have been removed from the substrate by an etch process. As such, theexposed portions of these layers 410, 412 and 414 and the exposedportions of those layers in the vias 420 are removed and the underlyinglayer 400 is exposed.

FIG. 23 depicts the substrate 350 with the etch resist removed. Inparticular, FIG. 23 depicts the components of the MEMS device formed astwo thin film beams 415 and 417 having MEMS components, such as shuttersand apertures. The thin film beams 415 and 417 extend essentiallyparallel to the surface of the substrate 350. The thin film beams 415and 417 are both connected to the substrate 350 but separated from thesubstrate 350 so that the thin film beams 415 and 417 are suspended awayfrom the surface of the substrate 350. The thin film beams 415 and 417are also separated from each other some distance and in theillustration, beam 415 is suspended above beam 417. In between the thinfilm components are layers of photoresist and mold material that wereused to form the shape and pattern of the thin film layers, andtherefore the components of the MEMS device.

FIG. 24 shows the MEMS device with the photoresist material that made upthe mold around which the devices were formed, stripped away. FIG. 24depicts that the MEMS device includes a first thin film beam 417 andthen a second thin film beam 415. The beams are arranged between andspaced a distance from the substrate 350. There is an anchor 430 thathas a portion of layer 384, in some implementations a conductive layer,in contact with the conductive surface 358. The two beams 415 and 417attach to the anchor 430 and they are held away from the substrate 350.The anchor 430 may, in some implementations, connect the beams 415 and417 to the conductive surface 358.

The materials described above may be deposited by sputtering, chemicalvapor deposition, or any other suitable technique and may extend acrossthe entire surface of the resist material, or over portions of thatsurface, and how the material is deposited will depend upon theapplication, the pattern, and the features being created. As notedabove, depositing, or any material, on a substrate may be achieved bysputtering, Chemical Vapor Deposition (CVD), electrodeposition, epitaxy,thermal oxidation, by physical reaction, Physical Vapor Deposition(PVD), atomic layer deposition, sputtering, casting, or any othertechnique for chemically or physically moving a material on to thesubstrate. Deposition may or may not be conformal, depending upon theapplication and goals of the process operation. The deposited materialsmay be passivated to prevent problems such as stiction between surfaces.Passivation may be by fluoridation, silanization, hydrogenation, or anysuitable process. Typically, the deposited materials are a thin filmhaving a thickness anywhere between a few nanometers to about 100micrometers. The deposition of a pattern mold may be by any suitablemethod. In some implementations the mold may be a hard mask formed or asuitable material, such as a layer of molybdenum (Mo) that is depositedby sputtering on the surface of an annealed resist. Patterning can takeplace through any suitable process, such as a chemical wash or a dryetch, or any other suitable technique. Etch processes may include wet ordry etch processes. Wet etching processes may include any process thatemploys a solvent, such as potassium hydroxide (KOH), to dissolvematerial being removed from the substrate. Dry etching may includesputtering away or dissolving using reactive ions or a vapor phaseetching. Both wet and dry etching processes may be anisotropic and/orisotropic.

TABLE 1 Example Passivation Deposition Process Material ConditionsTemperature/timing Operation CVD, etc. SiNx Before beam 1 deposition andPlasma CVD, PVD, after beam 1 etch and strip. Evaporation, 220° C. asbaseline in some examples, and typically between 100° C.-220° C. In someimplementations the higher temperature may be based in part on the baketemperature for the mold resist. SiOxNy Before beam 1 deposition andPlasma CVD, PVD, after beam 1 etch and strip. Evaporation, 220° C. asbaseline in some examples, and typically between 100° C.-220° C. In someimplementations the higher temperature may be based in part on the baketemperature for the mold resist. SiO2 Before beam 1 deposition andPlasma CVD, PVD, after beam 1 etch and strip. Evaporation, 220° C. asbaseline in some examples, and typically between 100° C.-220° C. In someimplementations the higher temperature may be based in part on the baketemperature for the mold resist. AlOx Before beam 1 deposition and ALD,PVD, after beam 1 etch and strip. Anodization 105-120° C. in someexamples for H₂O/TMA ALD system. Optionally, physically etched by highbias plasma etch. Anodization: After Al deposition, anodization toconvert Al to Al2O3. Diamond Before beam 1 deposition and Plasma CVDLike after beam 1 etch and strip. Carbon 220° C. as baseline in someexamples, and typically between 100° C.-220° C. In some implementationsthe higher temperature may be based in part on the bake temperature forthe mold resist. AlNx Before beam 1 deposition and Reactive Sputter,after beam 1 etch and strip. Evaporation, Nitration 220° C. as baselinein some by NH₃ plasma after examples, and typically between Aldeposition. 100° C.-220° C. In some implementations the highertemperature may be based in part on the bake temperature for the moldresist.

FIG. 25 is a flow chart of a process for forming a MEMS device firstbeam and a second beam. Specifically, FIG. 25 shows a process 2500 thatstarts at operation 2502 and provides a substrate having a conductivepad on a substrate. In operation 2504, a mold is deposited on thesubstrate to form a first thin film beam. The mold may be, in someimplementations, laid down as a layer of resist material that ispatterned to provide the shape and form of the different components thatmake up the device. In operation 2506, a layer of passivation materialis deposited on the mold. In operation 2508, the process deposits atleast one thin film layer on the passivation material to form at leastpart of the first thin film beam. The thickness of the layers beingdeposited, whether to form the mold or the beam, may vary according tothe application being addressed. In one implementation, the operation2504 deposits layers of resist material that are between 2 and 5 micronsin thickness, and in operations 2506 and 2508, layers of passivationmaterial or other semiconductor material that are between about 25 and125 angstroms are deposited. Depositing may be achieved by sputtering,CVD, PVD, or any other technique, including those earlier mentioned, forchemically or physically moving a material on to the substrate. Thefirst thin film beam may be formed by depositing a series of layers ofmaterial, each layer being a thin film layer that joins to the layer itis deposited on. The layers will follow the pattern of the mold andprovide the material that will form the different components that arebeing cast through the mold. The process 2500 in operation 2510 thendeposits a layer of passivation material over the first thin film beam.The passivation material, as described above, may be any suitablepassivation material that can provide a passivation coating to the beambeing formed from the layers deposited over the mold. The process 2500in operation 2512 deposits a mold over the layer of passivation materialfor forming a second thin film beam. This second mold can have a patternthat will form the components that will be part of the second beam ofthe device. In operation 2514, the process deposits at least one thinfilm layer over the mold to form a second thin film beam, and inoperation 2516, the process releases the first thin film beam and thesecond thin film beam from the mold to form a first beam having apassivation material on an exterior surface and being spaced from thesubstrate and a second beam spaced from and overlapping the first beam.

The process 2500 illustrates a process that forms a MEMS device havingtwo overlapping beams. However, the process 2500 is not limited toforming a device with two beams or with overlapping beams and may beused to form devices having more than two beams and beams which do notoverlap and are laterally spaced from each other.

FIG. 26 is a flow chart of a process for forming a stacked via.Specifically, FIG. 26 shows a flow chart for a process for making a MEMSdevice, such as the device manufactured using the process 2500 describedwith reference to FIG. 25, and providing that MEMS device with a stackedvia that can support two or more beams and suspend the beams away fromthe surface of a substrate. The process 2600 has an operation 2602 thatforms a via through a first thin film beam and a second thin film beamand extends the via to expose the conductive pad on the substrate. Theoperation 2602 provides the via to form an anchor within the via forsupporting the first thin film beam and the second thin film beam. Inoperation 2604, the process forms a side wall of the anchor from an armthat is connected to the first thin film beam and from an arm that isconnected to the second thin film beam. In operation 2606 the arm of thefirst thin film beam or the arm of the second thin film beam is providedwith a conductive material for connecting the first thin film beam orthe second thin film beam to the conductive pad. In operation 2608,either the first or the second thin film beam is connected to theconductive pad and the other thin film beam is spaced away from theconductive pad and electrically connected to the thin film beam that isconnected to the conductive pad. This provides an anchor that extends toboth beams and can carry electrical signals to both beams.

FIGS. 27A and 27B show an alternative implementation of a stacked via.FIG. 27A shows a via 2778, outlined with a box. This via 2778 may beformed using the process flow described with reference to FIG. 26,however the via 2778 employs a top surface of beam 2717 and a bottomsurface of beam 2715 as electrical contacts for connecting componentswithin beam 2715 and 2717 to the conductive layer 2758 on the substrate350. To this end, the via 2778 includes a series of conformal thin filmlayers including a layer 2710 of conductive material, such as aSi. Thedepicted layers are a conformal set of layers in that they follow thepattern formed by the resist layers 2770 and 2762. The conductive layer2710 is deposited on the bottom of the via 2778 and placed into contactwith the conducting surface 2758. This allows for an anchor to be formedwithin via 2778 and to have that anchor be in electrical contact withthe interconnect layer of the MEMs device. The via 2778 connects to andsupports the first beam 2717 and connects to and supports the secondbeam 2717. The layer 2710 extends into the second beam 2715. The layer2710 also contacts and makes an electrical connection to a layer 2712that also may be a conductive material such as aSi and that extendsthrough the first beam 2717. FIG. 27B shows the anchor 2711 formed byreleasing the conformal layers deposited on the via 2778 formed in theresist layers 2770 and 2762 and shown in FIG. 27A. The anchor 2711 has alayer 2714 of passivation material around its exterior. The anchor 2711holds the two beams 2715 and 2717 away from the surface of the substrateand connects the two beams to the conductive layer 2758.

FIGS. 28-41 show cross-sectional schematic views illustrating variousstages of manufacturing an example MEMS device 502, according to someimplementations. The MEMS device 502 may form one or more lightmodulators within a display. For example, the MEMS device 502 mayinclude a first thin film beam 617 and a second thin film beam 615 thatform one or more light modulators within the display. The MEMS device502 may form one or more pixels within the display. The stages formanufacturing the MEMS device 502 may include different, fewer, oradditional operations than illustrated in FIGS. 28-41.

FIG. 28 shows an example of a partially fabricated MEMS device. Thepartially fabricated MEMS device can include a substrate 550, a metallayer 552 on the substrate 550, and an insulating layer 554 on the metallayer 552. In some implementations, the substrate 550 can include anysuitable substrate material, such as glass. The insulating layer 554 maybe recessed and filled with conductive material 558, where theconductive material 558 forms a pad that contacts the metal layer 552.In some implementations, the conductive material 558 includes ITO orsome other suitable material for providing an electrical connection withthe metal layer 552. The conductive material 558 can conduct electricalsignals sufficiently to provide electrical signals to components of thepixels of the display. A first mold can be formed over a portion of theinsulating layer 554, where the first mold can include a layer ofphotoresist 562. The layer of photoresist 562 can include vias 578 thatcan expose the conductive material 558. The vias 578 permit depositionof materials onto the conductive material 558. The first mold canfurther include a mold layer 570, where the mold layer 570 can be formedof a photoresist material and formed over the layer of photoresist 562.The mold layer 570 can include trenches 574 that expose portions of thelayer of photoresist 562. The trenches 574 and vias 578 provide featuresof the first mold that can shape components of the MEMS device, such asthe shutter. The first mold can be patterned for forming a first thinfilm beam of the MEMS device. A first passivation layer 582 is formed onthe first mold and on the conductive material 558. The first passivationlayer 582 is conformally deposited on the first mold, including thelayer of photoresist 562 and the mold layer 570. The first passivationlayer 582 can be made of any suitable passivation material describedearlier herein. The first passivation layer 582 may be conformal alongthe sidewalls of the trenches 574 and vias 578 and also contact theconductive material 558. The first passivation layer 582 may be apassivation layer provided prior to release of the MEMS device. Thepartially fabricated MEMS device may be similar to the partiallyfabricated MEMS device described with respect to FIGS. 4-7.

In FIG. 29, a first mask 590 may be formed over the first mold. Thefirst mask 590 may be disposed over select locations so as to be formedover the mold layer 570 and the layer of photoresist 562. In someimplementations, the first mask 590 can be formed in and over thetrenches 574, but not formed in the vias 578 so that a contact etch canbe performed. The first mask 590 can be deposited over the firstpassivation layer 582. The first mask 590 can be made of a suitable etchresist material to allow for an etch process to remove portions of thefirst passivation layer 582 within the vias 578.

FIG. 30 shows the partially fabricated MEMS device after removal of thefirst passivation layer 582 within the vias 578. An etch process, suchas a selective dry etch process, can remove some of the firstpassivation layer 582 to expose the conductive material 558. Portions ofthe first passivation layer 582 not protected by the first mask 590 areetched away or otherwise removed. However, it will be understood by aperson of ordinary skill in the art that removal of the portions of thefirst passivation layer 582 within the vias 578 may occur without thefirst mask 590. In some implementations, a portion of the firstpassivation layer 582 on the conductive material 558 may be removedusing an anisotropic etch process without the first mask 590. In someimplementations, another portion of the first passivation layer 582 mayremain on the sidewalls of the vias 578.

FIG. 31 shows the partially fabricated MEMS device after the first mask590 is removed. The etch resist material of the first mask 590 may bestripped so that the first passivation layer 582 is exposed. The firstpassivation layer 582 remains on the first mold, but not along thesidewalls of the via 578 or on the conductive material 558.

In FIG. 32, additional layers are deposited over the first mold. Aconductive layer 584 is formed over the first mold, including over thelayer of photoresist 562 and the mold layer 570. The conductive layer584 can include any suitable material for carrying an electrical signalwithin the MEMS device, such as aSi, Ti, or Al. The conductive layer 584may be conformally deposited on the first passivation layer 582 as wellas along the sidewalls of the vias 578 and on the conductive material558. Thus, the conductive layer 584 may be in electrical contact withthe conductive material 558. A metallic layer 586 may be formed on theconductive layer 584. The metallic layer 586 may be conformallydeposited on the conductive layer 584. In some implementations, themetallic layer 586 may also be conductive and capable of carrying anelectrical signal within the MEMS device. In some implementations, themetallic layer 586 may be opaque or otherwise capable of substantiallyblocking the transmission of visible light. In some implementations, oneor both of the metallic layer 586 and the conductive layer 584 may besubstantially opaque, where one or both of the metallic layer 586 andthe conductive layer 584 is capable of substantially blocking thetransmission of visible light. For example, one or both of the metalliclayer 586 and the conductive layer 584 may be capable of blocking 80% ormore, 90% or more, or 95% or more of visible light. The layers 584 and586 may form the constituent layers of the first thin film beam of theMEMS device.

After the deposition of layers 582, 584, and 586, a second mask 596 maybe formed over the layers 582, 584, and 586 for patterning and formingthe first thin film beam. As illustrated in FIG. 34, the second mask 596may be formed over the layers 582, 584, and 586 in a pattern for formingcomponents of the first thin film beam of the MEMS device. In someimplementations, the second mask 596 may be formed over the vias 578 andat least one of the trenches 574. In some implementations, the secondmask 596 may include any suitable etch resist material.

In FIG. 34, an etch process is performed to remove portions of themetallic layer 586 and the conductive layer 584 not covered by thesecond mask 596. The etch process can include any suitable etch process,such as a dry etch or a wet etch. The etch process can remove both themetallic layer 586 and the conductive layer 584 over the top surfaces ofthe first mold. In some implementations, the etch process can remove themetallic layer 586 from the sidewalls of the trenches 574 while leavingthe conductive layer 584 on the sidewalls of the trenches 574 intact.The etch process can be an anisotropic etch process to leave portions ofthe conductive layer 584 and the first passivation layer 582 on thesidewalls of the trenches 574.

FIG. 35 shows the partially fabricated MEMS device after the second mask596 is removed. The etch resist material of the second mask 596 may bestripped so that the layers 582, 584, and 586 are exposed. Remainingportions of the conductive layer 584 and/or the metallic layer 586 canform the first thin film beam of the MEMS device.

A second passivation layer 594 is formed over the first thin film beamas illustrated in FIG. 36. The second passivation layer 594 may beconformally deposited on the first thin film beam and over the firstmold. In FIG. 36, the second passivation layer 594 covers exposedsurfaces of the layer of photoresist 562, the mold layer 570, theconductive layer 584, and the metallic layer 586. In someimplementations, the second passivation layer 594 conformally covers thesidewalls and bottom walls of the trenches 574. The second passivationlayer 594 can be made of any suitable passivation material describedearlier herein.

In FIG. 37, a third mask 598 is formed for selectively removing portionsof the second passivation layer 594. The third mask 598 can include anetch resist material and formed at select locations to protect thesecond passivation layer 594 on certain features of the MEMS device. Thepattern of the third mask 598 can be formed to allow an etch process toremove portions of the second passivation layer 594 from the first mold.That way, components of the first thin film beam can have at least apartially passivated exterior surface. In some implementations, thethird mask 598 can be formed over locations where the second passivationlayer 594 is formed over both the metallic layer 586 and the conductivelayer 584.

In FIG. 38, portions of the second passivation layer 594 are removed byan etch process. The etch process can remove the portions of the secondpassivation layer 594 not covered by the third mask 598. However, itwill be understood by a person of ordinary skill in the art that someportions of the second passivation layer 594 may be removed without thethird mask 598. In some implementations, such portions of the secondpassivation layer 594 may be removed without the third mask 598 by ananisotropic etch process so that the second passivation layer 594 mayremain intact on sidewalls of the partially fabricated MEMS device. Insome implementations, the etch process can be an anisotropic dry etchprocess, such as a CF₄ plasma etch process.

FIG. 39 shows the partially fabricated MEMS device with first thin filmbeam, where the first thin film beam includes components 583 and 585that are passivated by the first passivation layer 582 and the secondpassivation layer 594. The third mask 598 is removed in FIG. 39, wherethe etch resist material of the third mask 598 may be stripped. Betweencomponents 583 and 585 are passivating materials. The passivatingmaterials can prevent electrical shorts. In some implementations, thecomponents 583 and 585 of the first thin film beam can include one ormore actuators, shutters, and anchors. One or more anchors may connectto the substrate 550 at the conductive material 558 to provide a stableand secure attachment for the first thin film beam. One or more shuttersmay be a movable mechanical component configured to substantiallyprevent transmission of visible light, such as transmission of visiblelight through one or more apertures. The shutters may be movable betweenan open and closed position, where one or more actuators can beimplemented for controlling movement of the shutters. The one or moreactuators may include electrodes, where the electrodes can carryelectrical signals for controlling the movement of the shutters.

FIG. 40 shows an example of a MEMS device 502 with a first thin filmbeam 617 and a second thin film beam 615 over the first thin film beam617. The MEMS device 502 may be released from the first mold and from asecond mold. The first thin film beam 617 includes one or moreelectrodes 503 and 513. In some implementations, the one or moreelectrodes 503 and 513 can include movable sidewall beams having anaspect ratio of greater than about 4 to 1, and perhaps more than 16 to1, to provide narrow profile and a flexible beam that can be moved byapplication of an electromotive force. In some implementations, thefirst thin film beam 617 further includes one or more shutters 502. Thesecond thin film beam 615 is positioned over the first thin film beam617, where the first thin film beam 617 is arranged between thesubstrate 550 and the second thin film beam 615 and spaced away from thesubstrate 550 and the second thin film beam 615. The second thin filmbeam 615 is shown spaced over the first thin film beam 617 andoverlapping the first thin film beam 617. The second thin film beam 615includes one or more apertures 555. The one or more shutters 502 may beconfigured to substantially prevent light from traveling through the oneor more apertures 555. An inner passivation layer 530 partially coversan exterior surface of the second thin film beam 615 and partiallycovers an exterior surface of the first thin film beam 617.

In some implementations, the first thin film beam 617 includes a firstarm and the second thin film beam 615 includes a second arm, each armextending towards the surface of the substrate 550, where the first armis joined to and overlapping the second arm to form an anchor capable ofholding the first thin film beam 617 and the second thin film beam 615at a distance away from the substrate 550.

Fabrication of the second thin film beam 615 may be similar to thefabrication of the second thin film beam 415 in FIG. 24, where theprocess flow can be similar to the process flow shown in FIGS. 15-23.After forming the first thin film beam 617 over the first mold andcovering the first thin film beam 617 with passivation layers 582 and594, the second thin film beam 615 can be formed over the first thinfilm beam 617. A second mold is formed over the first thin film beam617. Then at least an additional conductive layer and an additionalmetallic layer is deposited and patterned over the second mold to formthe second thin film beam 615. In some implementations, a thirdpassivation layer 614 is formed over the second thin film beam 615. Thethird passivation layer 614 can include any suitable passivationmaterial as described earlier herein. The MEMS device 502 can bereleased by removing the first mold and the second mold, as shown inFIG. 40. The passivation layers 582, 594, and 614 are formed prior torelease. The inner passivation layer 530 can include the passivationlayers 582, 594, and 614.

In FIG. 40, the one or more electrodes 503, 513 may have one or moreexposed surfaces. The one or more exposed surfaces may not bepassivated, which can lead to a leakage path for electrical currents.The leakage path may result due to a difference in electric potentialsbetween electrodes. Each of the one or more electrodes 503 and 513 mayhave a top surface, a bottom surface, and sidewalls. As shown in FIG.40, the top surfaces of the electrodes 503 and 513 may be exposed, whilethe sidewalls and bottom surfaces of the electrodes 503 and 513 arepassivated by the first passivation layer 582 or the second passivationlayer 594. To cap the top surfaces of the electrodes 503 and 513 and anyother exposed surfaces in the first thin film beam 617 and the secondthin film beam 615, an additional layer of passivation material may beprovided to the MEMS device 502 after release.

FIG. 41 shows the MEMS device 502 with a post-release passivation layer500. After release of the MEMS device 502, the post-release passivationlayer 500 may be formed to cover the exterior surfaces of the first thinfilm beam 617 and the second thin film beam 615. In addition, thepost-release passivation layer 500 may constitute an outer passivationlayer that covers the inner passivation layer 530. The post-releasepassivation layer 500 may be conformally deposited on exposed surfacesof the MEMS device 502 by CVD, such as plasma CVD. However, it will beunderstood by a person of ordinary skill in the art that any suitabledeposition technique may be applied. The post-release passivation layer500 may include any suitable passivating material as described earlierherein. In some implementations, the MEMS device 502 can include aplurality of spacers for holding a plate away from the second thin filmbeam 615.

Deposition of the post-release passivation layer 500 may occur on allsurfaces of the MEMS device 502, as shown in FIG. 41. Put another way,the post-release passivation layer 500 coats everywhere on the MEMSdevice 502. However, the coating may not be uniform across all surfacesof the MEMS device 502. For example, the one or more apertures 555combined with the one or more shutters 502 may present difficulties forcoating some of the surfaces more than others. Precursors for CVD mayhave to come under and around the one or more apertures 555 and the oneor more shutters 502 to coat some of the surfaces of the MEMS device502. The post-release passivation layer 500 ensures coverage of exposedsurfaces of the MEMS device 500. As shown in FIG. 41, the post-releasepassivation layer 500 can cover top surfaces of the one or moreelectrodes 503 and 513. In some implementations, the post-releasepassivation layer 500 may be relatively thin, such as less than about1000 Å, less than about 500 Å, or between about 200 Å and about 400 Å.Thus, even though the deposition of the post-release passivation layer500 may be non-uniform, the impact of such non-uniformity may be smallwhen the post-release passivation layer 500 is relatively thin. Incontrast, the inner passivation layer 530 may have a thickness of lessthan about 2000 Å, such as between about 300 Å and about 1000 Å.

FIG. 41 shows the MEMS device 502 fully encapsulated and passivated.Rather than simply applying pre-release passivation layers to exteriorsurfaces in FIGS. 4-27, FIGS. 28-41 show various stages of manufacturingthe MEMS device 502 by applying both pre-release passivation layers 582,594, and 614 and a post-release passivation layer 500. In someimplementations, if only pre-release passivation layers 582, 594, and614 were applied, some surfaces of the MEMS device 502 may be leftexposed, such as the top surfaces of the electrodes 503 and 513. In someimplementations, if only post-release passivation layer 500 wereapplied, non-uniformities from coating the MEMS device 502 may have amore substantial impact. To coat everywhere in the MEMS device 502without pre-release passivation layers 582, 594, and 614, thickerdeposition of the post-release passivation layer 500 may be applied.However, thicker deposition of the post-release passivation layer 500can result in, for example, distortion in the one or more apertures 555.In addition, thicker deposition of the post-release passivation layer500 can lead to device performance non-uniformity. For example, edges ofthe MEMS device 502 can get much thicker, which can lead to higherpull-in voltages and different shutter speeds. Furthermore, anon-uniform post-release passivation layer 500 can cause tip gapnon-uniformity.

FIGS. 42A-42D show cross-sectional schematic views illustrating variousstages of passivating a thin film beam on a mold. In FIG. 42A, a firstpassivation layer 582 is conformally deposited on a top surface andsidewalls of a mold layer 570 and is conformally deposited on a topsurface of a layer of photoresist 562. In some implementations, thefirst passivation layer 582 can include SiN_(x). Furthermore, aconductive layer 584 can be conformally deposited on the firstpassivation layer 582. In some implementations, the conductive layer 584can include aSi.

In FIG. 42B, portions of the conductive layer 584 are removed while thefirst passivation layer 582 remains conformal along the top surfaces andsidewalls of the mold layer 570 and the layer of photoresist 562.Another portion of the conductive layer 584 remains intact that is onthe first passivation layer 582 and adjacent to the sidewalls of themold layer 570.

In FIG. 42C, a second passivation layer 594 is conformally deposited onthe first passivation layer 582 and on the conductive layer 584. In someimplementations, the second passivation layer 594 can have the samecomposition as the first passivation layer 582. The second passivationlayer 594 can cover exposed surfaces of the conductive layer 584 and addto the thickness of the first passivation layer 582.

In FIG. 42D, portions of the second passivation layer 594 and the firstpassivation layer 582 are removed from the top surfaces of the moldlayer 570 and the layer of photoresist 562. However, removal of theportions of the second passivation layer 594 and the first passivationlayer 582 can also leave portions of the conductive layer 584 exposed.This can result in some surfaces of a MEMS device not being passivated,which can lead to leakage of electrical currents. In someimplementations, components that are not passivated in a MEMS device caneven lead to an electrical short. Exposed surfaces of the conductivelayer 584 can similarly result from the process flow shown in FIGS.28-40. Thus, a post-release passivation layer 500 can provide a coatingfor covering any such exposed surfaces to eliminate or otherwise reduceleakage paths in a MEMS device.

FIGS. 43-52 show cross-sectional schematic views illustrating variousstages of manufacturing an example MEMS device 702, according to someother implementations. The process flow in FIGS. 43-52 can be similar tothe process flow in FIGS. 28-41, except with fewer masks. The MEMSdevice 702 may form one or more light modulators within a display. Insome implementations, the MEMS device 702 can include a first thin filmbeam 817 and a second thin film beam 815 that form the one or more lightmodulators within the display. The MEMS device 702 may form one or morepixels within the display. The stages for manufacturing the MEMS device702 may include different, fewer, or additional operations thanillustrated in FIGS. 43-52.

FIG. 43 shows an example of a partially fabricated MEMS device. Thepartially fabricated MEMS device can include a substrate 750, a metallayer 752, an insulating layer 754, conductive material 758, a layer ofphotoresist 762, a mold layer 770, a first passivation layer 782, andtrenches 774, and vias 778. The layer of photoresist 762 and the moldlayer 770 can form a first mold, where the first mold includes featuresfor shaping components of the MEMS device. The partially fabricated MEMSdevice in FIG. 43 can be similar to the partially fabricated MEMS devicein FIG. 28. Therefore, how the substrate 750, the metal layer 752, theinsulating layer 754, the conductive material 758, the layer ofphotoresist 762, the mold layer 770, the first passivation layer 782,and the trenches 774 and vias 778 are formed and arranged can be similarhow the substrate 550, the metal layer 552, the insulating layer 554,the conductive material 558, the layer of photoresist 562, the moldlayer 570, the first passivation layer 582, and the trenches 574 andvias 578 are formed and arranged.

In FIG. 44, portions of the first passivation layer 782 are removed inthe partially fabricated MEMS device. No mask is applied in removingsuch portions of the first passivation layer 782. Rather, an etchprocess, such as an anisotropic dry etch process, is applied to removethe portions of the first passivation layer 782. The first passivationlayer 782 may be etched from the top surfaces of the first mold,including the top surfaces of the layer of photoresist 762 and the moldlayer 770, as well as from the conductive material 758. Other portionsof the first passivation layer 782 may remain intact on the sidewalls ofthe trenches 774 and vias 778.

In FIG. 45, additional layers are formed over the first mold. Aconductive layer 784 is formed over the first mold and the firstpassivation layer 782, where the conductive layer 784 can be conformallydeposited on the layer of photoresist 762, the mold layer 770, the firstpassivation layer 782, and the conductive material 758. In someimplementations, the conductive layer 784 can include aSi. Thus, theconductive layer 784 may be in electrical contact with the conductivematerial 758. A metallic layer 786 may be formed on the conductive layer784, where the metallic layer 786 is conformal along the conductivelayer 784. In some implementations, the metallic layer 786 can includeTi. Further, an etch stop layer 788 may be formed on the metallic layer786, where the etch stop layer 788 is conformal along the metallic layer786. In some implementations, the etch stop layer 788 may be identicalin composition with the conductive layer 784. For example, the etch stoplayer 788 can include aSi. The etch stop layer 788 may also be referredto as a second conductive layer 788. The etch stop layer 788 mayfunction as an etch stop and protect the metallic layer 786. In someimplementations, one or more of the layers 784, 786, and 788 may beopaque or substantially opaque. For example, one or more of theconductive layer 784, the metallic layer 786, and the etch stop layer788 may be capable of blocking 80% or more, 90% or more, or 95% or moreof visible light. The layers 784, 786, and 788 may form the constituentlayers of the first thin film beam of the MEMS device.

FIG. 46 shows a partially fabricated MEMS device with a first mask 790formed over the layers 782, 784, and 786 for forming the first thin filmbeam. As illustrated in FIG. 46, the first mask 790 may be provided overselect locations for forming the first thin film beam. In someimplementations, the first mask 790 may be formed over the vias 778 andat least one of the trenches 774. In some implementations, the firstmask 790 may include any suitable etch resist material.

Portions of the layers 784, 786, and 788 are removed in FIG. 47,including portions not covered by the first mask 790. An etch processcan include any suitable etch process, such as a dry etch or a wet etch.The etch process can remove the conductive layer 784, the metallic layer786, and the etch stop layer 788 from the top surfaces of the firstmold. In some implementations, the etch process can remove the metalliclayer 786 and the etch stop layer 788 on the sidewalls of the trenches774 while leaving the conductive layer 784 on the sidewalls of thetrenches 774 intact. In some implementations, the etch process caninclude an isotropic etch of the etch stop layer 788, an isotropic etchof the metallic layer 786, and an anisotropic etch of the conductivelayer 784. The anisotropic etch of the conductive layer 784 can leaveportions of the conductive layer 784 and the first passivation layer 782on the sidewalls of the trenches 774 intact.

FIG. 48 shows the partially fabricated MEMS device after the first mask790 is removed. The etch resist material of the first mask 790 may bestripped so that layers 782, 784, 786, and/or 788 are exposed. Remainingportions of the conductive layer 784, the metallic layer 786, and/or theetch stop layer 788 form components of the first thin film beam of theMEMS device.

In FIG. 49, a second passivation layer 794 is formed over the first thinfilm beam. The second passivation layer 794 may be conformally depositedon the first thin film beam and over the first mold. In someimplementations, the second passivation layer 794 covers exposedsurfaces of the layer of photoresist 762, the mold layer 770, the firstpassivation layer 782, the conductive layer 784, the metallic layer 786,and the etch stop layer 788. In some implementations, the secondpassivation layer 794 conformally covers the sidewalls and bottom wallsof the trenches 774. The second passivation layer 794 may be made of anysuitable passivation material described earlier herein.

FIG. 50 shows a partially fabricated MEMS device with portions of thesecond passivation layer 794 removed. No mask is applied in removingsuch portions of the second passivation layer 794. Instead, an etchprocess, such as an anisotropic dry etch process, is applied to removethe portions of the second passivation layer 794. The second passivationlayer 794 may be etched from the top surfaces of the first thin filmbeam, including the top surfaces of the etch stop layer 788 and theconductive layer 784. The second passivation layer 794 may also beetched from the top surfaces of the layer of photoresist 762 and themold layer 770. The etch stop layer 788 may serve as an etch stop sothat the portions of the second passivation layer 794 are removedwithout removing the layers 784 and 786 of the first thin film beam.Other portions of the second passivation layer 794 may remain intact onthe sidewalls of the trenches 774 and vias 778.

FIG. 51 shows an example of a MEMS device 702 with a first thin filmbeam 817 and a second thin film beam 815 over the first thin film beam817. The MEMS device 702 may be released from the first mold and asecond mold. The first thin film beam 817 includes one or moreelectrodes 703 and 713. In some implementations, the one or moreelectrodes 703 and 713 can include movable sidewall beams having anaspect ratio of greater than about 4 to 1, and perhaps more than 16 to1, to provide narrow profile and a flexible beam that can be moved byapplication of an electromotive force. In some implementations, thefirst thin film beam 817 includes one or more shutters 702. The secondthin film beam 815 is positioned over the first thin film beam 817,where the first thin film beam 817 is arranged between the substrate 750and the second thin film beam 815 and spaced away from the substrate 750and the second thin film beam 815. The second thin film beam 815 isshown spaced over the first thin film beam 817 and overlapping the firstthin film beam 817. The second thin film beam 815 includes one or moreapertures 755. The one or more shutters 702 may be configured tosubstantially prevent light from traveling through the one or moreapertures 755. An inner passivation layer 730 partially covers anexterior surface of the second thin film beam 815 and partially coversan exterior surface of the first thin film beam 817.

In some implementations, the first thin film beam 817 includes a firstarm and the second thin film beam 815 includes a second arm, each armextending towards the surface of the substrate 750, where the first armis joined to and overlapping the second arm to form an anchor capable ofholding the first thin film beam 817 and the second thin film beam 815at a distance away from the substrate 750. The second thin film beam 815may be connected to the etch stop layer 788 at the anchor.

Fabrication of the second thin film beam 815 may be similar to thefabrication of the thin film beam 415 in FIG. 24, where the process flowcan be similar to the process flow shown in FIGS. 15-23. After formingthe first thin film beam 817 over the first mold and covering the firstthin film beam 817 with passivation layers 782 and 794, the second thinfilm beam 815 can be formed over the first thin film beam 817. A secondmold is formed over the first thin film beam 817. Then at least anadditional conductive layer and an additional metallic layer isdeposited and patterned over the second mold to form the second thinfilm beam 815. In some implementations, a third passivation layer 814 isformed over the second thin film beam 815. The third passivation layer814 can include any suitable passivation material discussed earlierherein. The MEMS device 702 can be released by removing the first moldand the second mold, as shown in FIG. 51. The passivation layers 782,794, and 814 are formed prior to release.

In FIG. 51, the one or more electrodes 703 and 713 may have one or moreexposed surfaces. The one or more exposed surfaces may not bepassivated, which can lead to a leakage path for electrical currents. Asshown in FIG. 51, the top surfaces and the bottom surfaces of theelectrodes 703 and 713 may be exposed, while the sidewalls of theelectrodes 703 and 713 are passivated by the first passivation layer 782or the second passivation layer 794. Moreover, the top and bottomsurfaces of the one or more shutters 702 may be exposed. To passivateany exposed surfaces in the first thin film beam 817 and the second thinfilm beam 815, an additional layer of passivation material may beprovided to the MEMS device 702 after release.

FIG. 52 shows the MEMS device 702 with a post-release passivation layer500. After release of the MEMS device 702, the post-release passivationlayer 700 may be formed to cover the exterior surfaces of the first thinfilm beam 817 and the second thin film beam 815. In addition, thepost-release passivation layer 700 may constitute an outer passivationlayer that covers the inner passivation layer 730. The post-releasepassivation layer 700 may be conformally deposited on exposed surfacesof the MEMS device 702 by CVD, such as plasma CVD. However, it will beunderstood by a person of ordinary skill in the art that any suitabledeposition technique may be applied. The post-release passivation layer700 may include any suitable passivating material as described earlierherein. In some implementations, the MEMS device 702 can include aplurality of spacers for holding a plate away from the second thin filmbeam 815.

Deposition of the post-release passivation layer 700 may occur on allsurfaces of the MEMS device 702, as shown in FIG. 52. Put another way,the post-release passivation layer 700 coats everywhere on the MEMSdevice 702. The post-release passivation layer 700 may cover topsurfaces and bottom surfaces of the one or more electrodes 703 and 713as well as the top surfaces and bottom surfaces of the one or moreshutters 702. In some implementations, the post-release passivationlayer 700 may be relatively thin, such as less than about 1000 Å, lessthan about 500 Å, or between about 200 Å and about 400 Å. In contrast,the inner passivation layer 730 may have a thickness of less than about2000 Å, such as between about 300 Å and about 1000 Å. Aspects of thepost-release passivation layer 700 in FIG. 52 may be similar to thepost-release passivation layer 500 in FIG. 41.

FIGS. 53A and 53B show system block diagrams of an example displaydevice 5340 that includes a plurality of display elements. The displaydevice 5340 can be, for example, a smart phone, a cellular or mobiletelephone. However, the same components of the display device 5340 orslight variations thereof are also illustrative of various types ofdisplay devices such as televisions, computers, tablets, e-readers,hand-held devices and portable media devices.

The display device 5340 includes a housing 5341, a display 5330, anantenna 5343, a speaker 5345, an input device 5348 and a microphone5346. The housing 5341 can be formed from any of a variety ofmanufacturing processes, including injection molding, and vacuumforming. In addition, the housing 5341 may be made from any of a varietyof materials, including, but not limited to: plastic, metal, glass,rubber and ceramic, or a combination thereof. The housing 5341 caninclude removable portions (not shown) that may be interchanged withother removable portions of different color, or containing differentlogos, pictures, or symbols.

The display 5330 may be any of a variety of displays, including abi-stable or analog display, as described herein. The display 5330 alsocan be capable of including a flat-panel display, such as plasma,electroluminescent (EL) displays, OLED, super twisted nematic (STN)display, LCD, or thin-film transistor (TFT) LCD, or a non-flat-paneldisplay, such as a cathode ray tube (CRT) or other tube device. Inaddition, the display 5330 can include a mechanical lightmodulator-based display, as described herein.

The components of the display device 5340 are schematically illustratedin FIG. 53B. The display device 5340 includes a housing 5341 and caninclude additional components at least partially enclosed therein. Forexample, the display device 5340 includes a network interface 5327 thatincludes an antenna 5343 which can be coupled to a transceiver 5347. Thenetwork interface 5327 may be a source for image data that could bedisplayed on the display device 5340. Accordingly, the network interface5327 is one example of an image source module, but the processor 5321and the input device 5348 also may serve as an image source module. Thetransceiver 5347 is connected to a processor 5321, which is connected toconditioning hardware 5352. The conditioning hardware 5352 may beconfigured to condition a signal (such as filter or otherwise manipulatea signal). The conditioning hardware 5352 can be connected to a speaker5345 and a microphone 5346. The processor 5321 also can be connected toan input device 5348 and a driver controller 5329. The driver controller5329 can be coupled to a frame buffer 5328, and to an array driver 5322,which in turn can be coupled to a display array 5330. One or moreelements in the display device 5340, including elements not specificallydepicted in FIG. 53A, can be capable of functioning as a memory deviceand be capable of communicating with the processor 5321. In someimplementations, a power supply 5350 can provide power to substantiallyall components in the particular display device 5340 design.

The network interface 5327 includes the antenna 43 and the transceiver5347 so that the display device 5340 can communicate with one or moredevices over a network. The network interface 5327 also may have someprocessing capabilities to relieve, for example, data processingrequirements of the processor 5321. The antenna 5343 can transmit andreceive signals. In some implementations, the antenna 5343 transmits andreceives RF signals according to any of the IEEE 16.11 standards, or anyof the IEEE 802.11 standards. In some other implementations, the antenna5343 transmits and receives RF signals according to the Bluetooth®standard. In the case of a cellular telephone, the antenna 5343 can bedesigned to receive code division multiple access (CDMA), frequencydivision multiple access (FDMA), time division multiple access (TDMA),Global System for Mobile communications (GSM), GSM/General Packet RadioService (GPRS), Enhanced Data GSM Environment (EDGE), TerrestrialTrunked Radio (TETRA), Wideband-CDMA (W-CDMA), Evolution Data Optimized(EV-DO), 1×EV-DO, EV-DO Rev A, EV-DO Rev B, High Speed Packet Access(HSPA), High Speed Downlink Packet Access (HSDPA), High Speed UplinkPacket Access (HSUPA), Evolved High Speed Packet Access (HSPA+), LongTerm Evolution (LTE), AMPS, or other known signals that are used tocommunicate within a wireless network, such as a system utilizing 3G, 4Gor 5G, or further implementations thereof, technology. The transceiver5347 can pre-process the signals received from the antenna 5343 so thatthey may be received by and further manipulated by the processor 5321.The transceiver 5347 also can process signals received from theprocessor 5321 so that they may be transmitted from the display device5340 via the antenna 5343.

In some implementations, the transceiver 5347 can be replaced by areceiver. In addition, in some implementations, the network interface5327 can be replaced by an image source, which can store or generateimage data to be sent to the processor 5321. The processor 5321 cancontrol the overall operation of the display device 5340. The processor5321 receives data, such as compressed image data from the networkinterface 5327 or an image source, and processes the data into raw imagedata or into a format that can be readily processed into raw image data.The processor 5321 can send the processed data to the driver controller5329 or to the frame buffer 5328 for storage. Raw data typically refersto the information that identifies the image characteristics at eachlocation within an image. For example, such image characteristics caninclude color, saturation and gray-scale level.

The processor 5321 can include a microcontroller, CPU, or logic unit tocontrol operation of the display device 5340. The conditioning hardware5352 may include amplifiers and filters for transmitting signals to thespeaker 5345, and for receiving signals from the microphone 5346. Theconditioning hardware 5352 may be discrete components within the displaydevice 5340, or may be incorporated within the processor 5321 or othercomponents.

The driver controller 5329 can take the raw image data generated by theprocessor 5321 either directly from the processor 5321 or from the framebuffer 5328 and can re-format the raw image data appropriately for highspeed transmission to the array driver 5322. In some implementations,the driver controller 5329 can re-format the raw image data into a dataflow having a raster-like format, such that it has a time order suitablefor scanning across the display array 5330. Then the driver controller5329 sends the formatted information to the array driver 5322. Althougha driver controller 5329 is often associated with the system processor5321 as a stand-alone Integrated Circuit (IC), such controllers may beimplemented in many ways. For example, controllers may be embedded inthe processor 5321 as hardware, embedded in the processor 5321 assoftware, or fully integrated in hardware with the array driver 5322.

The array driver 5322 can receive the formatted information from thedriver controller 5329 and can re-format the video data into a parallelset of waveforms that are applied many times per second to the hundreds,and sometimes thousands (or more), of leads coming from the display'sx-y matrix of display elements. In some implementations, the arraydriver 5322 and the display array 5330 are a part of a display module.In some implementations, the driver controller 5329, the array driver5322, and the display array 5330 are a part of the display module.

In some implementations, the driver controller 5329, the array driver5322, and the display array 5330 are appropriate for any of the types ofdisplays described herein. For example, the driver controller 5329 canbe a conventional display controller or a bi-stable display controller(such as a mechanical light modulator display element controller).Additionally, the array driver 5322 can be a conventional driver or abi-stable display driver (such as a mechanical light modulator displayelement controller). Moreover, the display array 5330 can be aconventional display array or a bi-stable display array (such as adisplay including an array of mechanical light modulator displayelements). In some implementations, the driver controller 5329 can beintegrated with the array driver 5322. Such an implementation can beuseful in highly integrated systems, for example, mobile phones,portable-electronic devices, watches or small-area displays.

In some implementations, the input device 5348 can be configured toallow, for example, a user to control the operation of the displaydevice 5340. The input device 5348 can include a keypad, such as aQWERTY keyboard or a telephone keypad, a button, a switch, a rocker, atouch-sensitive screen, a touch-sensitive screen integrated with thedisplay array 5330, or a pressure- or heat-sensitive membrane. Themicrophone 5346 can be configured as an input device for the displaydevice 5340. In some implementations, voice commands through themicrophone 5346 can be used for controlling operations of the displaydevice 5340. Additionally, in some implementations, voice commands canbe used for controlling display parameters and settings.

The power supply 5350 can include a variety of energy storage devices.For example, the power supply 5350 can be a rechargeable battery, suchas a nickel-cadmium battery or a lithium-ion battery. In implementationsusing a rechargeable battery, the rechargeable battery may be chargeableusing power coming from, for example, a wall socket or a photovoltaicdevice or array. Alternatively, the rechargeable battery can bewirelessly chargeable. The power supply 5350 also can be a renewableenergy source, a capacitor, or a solar cell, including a plastic solarcell or solar-cell paint. The power supply 5350 also can be configuredto receive power from a wall outlet.

In some implementations, control programmability resides in the drivercontroller 5329 which can be located in several places in the electronicdisplay system. In some other implementations, control programmabilityresides in the array driver 5322. The above-described optimization maybe implemented in any number of hardware and/or software components andin various configurations.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: a, b, or c” is intended to cover: a, b, c,a-b, a-c, b-c, and a-b-c.

The various illustrative logics, logical blocks, modules, circuits andalgorithm processes described in connection with the implementationsdisclosed herein may be implemented as electronic hardware, computersoftware, or combinations of both. The interchangeability of hardwareand software has been described generally, in terms of functionality,and illustrated in the various illustrative components, blocks, modules,circuits and processes described above. Whether such functionality isimplemented in hardware or software depends upon the particularapplication and design constraints imposed on the overall system.

The hardware and data processing apparatus used to implement the variousillustrative logics, logical blocks, modules and circuits described inconnection with the aspects disclosed herein may be implemented orperformed with a general purpose single- or multi-chip processor, adigital signal processor (DSP), an application specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or otherprogrammable logic device, discrete gate or transistor logic, discretehardware components, or any combination thereof designed to perform thefunctions described herein. A general purpose processor may be amicroprocessor, or, any conventional processor, controller,microcontroller, or state machine. A processor also may be implementedas a combination of computing devices, e.g., a combination of a DSP anda microprocessor, a plurality of microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration. In some implementations, particular processes and methodsmay be performed by circuitry that is specific to a given function.

In one or more aspects, the functions described may be implemented inhardware, digital electronic circuitry, computer software, firmware,including the structures disclosed in this specification and theirstructural equivalents thereof, or in any combination thereof.Implementations of the subject matter described in this specificationalso can be implemented as one or more computer programs, i.e., one ormore modules of computer program instructions, encoded on a computerstorage media for execution by, or to control the operation of, dataprocessing apparatus.

Various modifications to the implementations described in thisdisclosure may be readily apparent to those skilled in the art, and thegeneric principles defined herein may be applied to otherimplementations without departing from the spirit or scope of thisdisclosure. Thus, the claims are not intended to be limited to theimplementations shown herein, but are to be accorded the widest scopeconsistent with this disclosure, the principles and the novel featuresdisclosed herein.

Additionally, a person having ordinary skill in the art will readilyappreciate, the terms “upper” and “lower” are sometimes used for ease ofdescribing the figures, and indicate relative positions corresponding tothe orientation of the figure on a properly oriented page, and may notreflect the proper orientation of any device as implemented.

Certain features that are described in this specification in the contextof separate implementations also can be implemented in combination in asingle implementation. Conversely, various features that are describedin the context of a single implementation also can be implemented inmultiple implementations separately or in any suitable subcombination.Moreover, although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Further, the drawings may schematically depict one more exampleprocesses in the form of a flow diagram. However, other operations thatare not depicted can be incorporated in the example processes that areschematically illustrated. For example, one or more additionaloperations can be performed before, after, simultaneously, or betweenany of the illustrated operations. In certain circumstances,multitasking and parallel processing may be advantageous. Moreover, theseparation of various system components in the implementations describedabove should not be understood as requiring such separation in allimplementations, and it should be understood that the described programcomponents and systems can generally be integrated together in a singlesoftware product or packaged into multiple software products.Additionally, other implementations are within the scope of thefollowing claims. In some cases, the actions recited in the claims canbe performed in a different order and still achieve desirable results.

What is claimed is:
 1. A microelectromechanical systems (MEMS) devicecomprising: a substrate; a first thin film beam over the substrate,wherein the first thin film beam includes one or more electrodes; asecond thin film beam over the first thin film beam, the first thin filmbeam being arranged between the substrate and the second thin film beamand spaced away from the substrate and the second thin film beam,wherein the second thin film beam includes one or more apertures; aninner passivation layer partially covering an exterior surface of thesecond thin film beam and partially covering an exterior surface of thefirst thin film beam, wherein a portion of the first thin film beam anda portion of the second thin film beam are uncovered by the innerpassivation layer; and an outer passivation layer over the innerpassivation layer, the outer passivation layer covering the innerpassivation layer and the uncovered portion of the first thin film beamand the uncovered portion of the second thin film beam.
 2. The MEMSdevice of claim 1, wherein each of the one or more electrodes includes atop surface, a bottom surface, and sidewalls, the inner passivationlayer covering at least the sidewalls of the one or more electrodes, andthe outer passivation layer covering at least the top and bottomsurfaces of the one or more electrodes.
 3. The MEMS device of claim 1,wherein the first thin film beam includes a first conductive layer,wherein the substrate includes a conductive surface in contact with thefirst conductive layer.
 4. The MEMS device of claim 1, wherein the firstthin film beam further includes a second conductive layer, the secondconductive layer being identical in composition with the firstconductive layer and connected to the second thin film beam.
 5. The MEMSdevice of claim 4, wherein the second conductive layer is an etch stoplayer.
 6. The MEMS device of claim 4, wherein the first thin film beamfurther includes a metallic layer between the first conductive layer andthe second conductive layer, one or more of the first conductive layer,the metallic layer, and the second conductive layer being substantiallyopaque to light.
 7. The MEMS device of claim 1, wherein the first thinfilm beam includes a shutter, the shutter being configured tosubstantially prevent light from traveling through the one or moreapertures.
 8. The MEMS device of claim 1, wherein a thickness of thesecond passivation layer is less than about 1000 Å.
 9. The MEMS deviceof claim 1, wherein the first thin film beam includes a first arm andthe second thin film beam includes a second arm, each arm extendingtowards the surface of the substrate, the first arm being joined to andoverlapping the second arm, the first arm and the second arm forming ananchor capable of holding the first thin film beam and the second thinfilm beam a distance away from the substrate.
 10. The MEMS device ofclaim 1, wherein the one or more electrodes include movable sidewallbeams having an aspect ratio of greater than about 4:1.
 11. The MEMSdevice of claim 1, wherein the substrate includes a glass substrate. 12.The MEMS device of claim 1, further comprising a plurality of spacersfor holding a plate away from the second thin film beam.
 13. The MEMSdevice of claim 1, further comprising a processor capable ofcommunicating with the display, the processor being capable ofprocessing image data, and a memory device capable of communicating withthe processor.
 14. The MEMS device of claim 13, further comprising adriver circuit capable of sending at least one signal to the display;and a controller capable of sending at least a portion of the image datato the driver circuit.
 15. The MEMS device of claim 13, furthercomprising an image source module capable of sending the image data tothe processor, wherein the image source module includes at least one ofa receiver, transceiver, and transmitter.
 16. The MEMS device of claim13, further comprising an input device capable of receiving input dataand communicating the input data to the processor.
 17. A MEMS devicecomprising: a substrate; a first thin film beam over the substrate,wherein the first thin film beam includes one or more electrodes; asecond thin film beam over the first thin film beam, the first thin filmbeam being arranged between the substrate and the second thin film beamand spaced away from the substrate and the second thin film beam,wherein the second thin film beam includes one or more apertures; firstmeans for passivating the MEMS device partially covering an exteriorsurface of the second thin film beam and partially covering an exteriorsurface of the first thin film beam, wherein a portion of the first thinfilm beam and a portion of the second thin film beam are uncovered bythe first passivating means; and second means for passivating the MEMSdevice over the first passivating means, the second passivating meanscovering the first passivating means layer and the uncovered portion ofthe first thin film beam and the uncovered portion of the second thinfilm beam.
 18. The MEMS device of claim 17, wherein each of the one ormore electrodes includes a top surface, a bottom surface, and sidewalls,the first passivating means covering at least the sidewalls of the oneor more electrodes, and the second passivating means covering at leastthe top and bottom surfaces of the one or more electrodes.
 19. The MEMSdevice of claim 17, wherein the first thin film beam includes a firstconductive layer, wherein the substrate includes a conductive surface incontact with the first conductive layer.
 20. A device comprising: asubstrate; a conductive pad over the substrate; at least one first thinfilm layer contacting the conductive pad, wherein the at least one firstthin film layer form at least part of a first thin film beam; at leastone second thin film layer over the first thin film beam to form atleast part of a second thin film beam, wherein the first thin film beamis spaced away from the substrate and the second thin film beam isspaced away from and overlapping the first thin film beam; a firstpre-release passivation layer partially covering an exterior surface ofthe first thin film beam, wherein at least a portion of the first thinfilm beam is exposed; a post-release passivation layer over the firstpre-release passivation layer, wherein the post-release passivationlayer at least covers the exposed portion of the first thin film beam.21. The device of claim 20, further comprising: a second pre-releasepassivation layer partially covering an exterior surface of the secondthin film beam, wherein at least a portion of the second thin film beamis exposed, and wherein the post-release passivation layer covers theexposed portion of the second thin film beam.
 22. The device of claim20, wherein the at least one thin film layer comprises: a firstconductive layer contacting the conductive pad; and a metallic layerdisposed on the conductive layer, wherein at least one of the conductivelayer and the metallic layer is substantially opaque to light.
 23. Thedevice of claim 22, wherein the at least one thin film layer furthercomprises: a second conductive layer disposed on the metallic layer, thesecond conductive layer being identical in composition with the firstconductive layer.
 24. The device of claim 20, wherein the first thinfilm beam comprises: one or more electrodes; and one or more shutters.25. The device of claim 24, wherein the exposed portion of the firstthin film beam includes an exposed portion of the one or moreelectrodes.
 26. The device of claim 24, wherein the second thin filmbeam comprises: one or more apertures, wherein the one or more shuttersare configured to substantially prevent light from traveling through theone or more apertures.